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FOR THE PEOPLE 

FOR EDVCATION 

FOJ^fyfNEftJCE 






CANCELLED 

LIBRARY 

OF 

THE AMERICAN MUSEUM 

OF 

NATURAL HISTORY 





Sound an 
A.M.N.H.J 

mi J 



U. S. DEPARTMENT OF AGRICULTURE. 

Department Bulletins 

Nos. 76-100, 



WITH CONTENTS 
AND INDEX. 



Prepared in the Division of Publications. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1914. 



CONTENTS. 

/eT 6 6 J of ~>w*cl%9 

Department Bulletin 76. — Laboratory and Field Assay of Arsenical 

Dipping Fluids: Page. 

Introduction 1 

Laboratory methods 4 

Field methods of assay 10 

Field method for actual arsenious oxid 11 

Field method for " Total arsenic " 16 

The interpretation of results 17 

Department Bulletin 77.— Rocky Mountain Mine Timbers: 

Strength 1 

Consumption and durability 11 

Appendix 19 

Department Bulletin 78. — The So-called Tobacco Wireworm in Vir- 
ginia: 

Introduction 1 

General habits and economic importance of the group to which the tobacco 

crambus belongs 2 

Economic importance of the tobacco crambus 3 

Origin and distribution . 4 

Seasonal history 4 

Description 5 

Life history 7 

Natural enemies 13 

Repression 14 

Bibliography 29 

Department Bulletin 79. — Research Studies on the Curing of Leaf 
Tobacco: 

Introduction 1 

Nature of the curing process 2 

Loss in weight of dry matter in air curing when the leaf is primed 3 

Loss in weight of dry matter in air curing when the leaf is cured on the 

stalk- 7 

Effect of splitting the stalk on the -loss of weight in air curing 8 

Composition of cigar-wrapper leaf before and after curing 9 

Changes in composition of leaf tobacco in air curing 17 

Curing the leaves on the stalk compared with curing the picked leaves. . . 30 

Enzyms in tobacco curing 33 

Tobacco curing as affected by external conditions 36 

Summary 39 

Department Bulletin 80. — Effects of Varying Certain Cooking Condi- 
tions in Producing Soda Pulp from Aspen: 

Purpose of experiments 1 

The soda process and its application 2 

Previous investigations 4 

Methods of conducting experiments 9 

Test materials used 14 

3 



4 DEPARTMENT OF AGRICULTURE, BULLS. 76-100. 

Department Bulletin 80. — Effects of Varying Certain Cooking Con- 
ditions in Producing Soda Pulp from Aspen — Continued. page. 

Effects of variations in the cooking conditions 15 

Influence of cooking conditions on cost 31 

Summary 38 

Practical value of results 40 

Appendix 41 

Aspen as a raw material for paper pulp 41 

Paper pulp from aspen 44 

Records of the series tests 47 

Methods for auxiliary tests 54 

Autoclave tests on aspen 57 

Bibliography 61 

Department Bulletin 81. — The Potato Quarantine and the American 
Potato Industry: 

Introduction 1 

Review of the potato-disease situation 2 

Introduced parasites the more dangerous 2 

The wart disease 4 

Powdery scab 5 

Other reasons for potato regulations 10 

A general quarantine now in effect 12 

General explanation of regulations 13 

Relation of imported to domestic potatoes 15 

The 1913 potato crop 16 

A progressive policy needed '. 17 

Protection from disease 18 

Lack of an outlet for surplus potatoes 19 

Department Bulletin 82. — Powdery Scab (Spongospora Subterranea) 
of Potatoes: 

Introduction 1 

Common name of the disease caused by spongospora 2 

Scientific name of powdery scab 2 

Description of the disease 3 

Geographical distribution of powdery scab 5 

Presence of powdery scab in Canada 6 

Powdery scab in the United States 6 

Damage to the potato crop 7 

Effect on seed potatoes 7 

Is powdery scab a dangerous malady? 8 

Macroscopic differences between spongospora and oospora scab 10 

Function of the spore balls and methods of infection 11 

Seed treatment 12 

Soil treatment 12 

Sacks and barrels as agents in spreading powdery scab 14 

Bibliography 15 

Department Bulletin 83. — Farmers' Institute and Agricultural Ex- 
tension Work in the United States in 1913: 

Progress of farmers' institutes in 1913 1 

Growth of the institutes during the last decade 3 

Administrative methods 4 

Association of farmers' institute workers 7 

Extension work by the agricultural colleges 8 

Section on extension work of the association of American agricultural 

colleges and experiment stations 10 



CONTENTS. 5 

Department Bulletin 83. — Farmers' Institute and Agricultural Ex- 
tension Work in the United States in 1913 — Continued. Page. 

Illustrated lectures 11 

Correspondence schools 11 

Aid to agriculture by transportation companies 12 

Agricultural extension work in foreign countries 13 

State reports 19 

State officials in charge of farmers' institutes 24 

Statistics of farmers' institutes, 1913 26 

Statistics of agricultural extension, 1913 34 

Department Bulletin 84. — Experiments with Udo, the New Japanese 
Vegetable: 

Introduction 1 

Early experiments with udo 5 

Relatives of udo • 6 

Varieties of udo 7 

Method of culture 8 

The blanching of the shoots 10 

Preparation for the table 12 

Recipes 13 

Climatic requirements of udo 14 

Diseases of udo 14 

Reasons for the introduction of udo 14 

Department Bulletin 85. — The Cost op Pasteurizing Milk and Cream: 

Introduction 1 

Tests of milk-pasteurizing apparatus 2 

Tests of cream-pasteurizing apparatus 6 

Conclusions 12 

Department Bulletin 86. — Tests op Wooden Barrels: 

Object of the tests. 1 

Material 1 

Barrel tests 2 

Minor tests : 3 

Results 4 

General observations of nature of failures 5 

Changes in design as indicated by the character of the failures 5 

Tests of made-up barrels 6 

Suggestions regarding tests of shipping containers 7 

Department Bulletin 87. — Flumes and Fluming: 

Increasing importance of flumes 1 

Forms of lumber transported by flumes 2 

Types of flumes 3 

Feeders 17 

Tunneling 18 

Small holding reservoirs at different points of flume 19 

Reservoir ponds at head of flumes 20 

Branch flumes 22 

Switches and Y's 22 

The use of "snubs" in unloading material from a flume 23 

Reinforcement of flumes at points where extensive loading is to be done. . 23 

Telephones a valuable adjunct to flume operation 25 

Sawed material for stringers, sills, braces, etc., not a necessity, but usually 

more economical 25 

Water used in fluming sometimes available for irrigation purposes 26 

Brailing and accoutering lumber 26 



6 DEPARTMENT OF AGRICULTURE, BULLS. 76-100. 

Department Bulletin 87. — Flumes and Fluming — Continued. page. 

Planing mills should be located at lower end of flume 27 

Size and carrying capacity of flumes for different classes of material 27 

Cost of transporting different classes of material 29 

Cost of construction 30 

Distance between bents 31 

Advisable method of nailing 32 

Department Bulletin 88. — The Control of the Codling Moth in the 
Pecos Valley in New Mexico: 

Introduction 1 

Experiments in the Sherman and Johnson orchard 2 

Places of entrance of fruit by codling moth larvae 5 

Recommendations based on the foregoing results 7 

Department Bulletin 89. — The Death of Chestnuts and Oaks Due to 
Armillaria Mellea: 

Introduction 1 

Character of the timber examined 1 

Character of data obtained 1 

General condition of the chestnut 2 

General condition of the white oak 4 

Armillaria mellea on chestnuts, oaks, and poplars 4 

General discussion of the diseased chestnuts and oaks 6 

Area infected by armillaria mellea 7 

Armillaria mellea on chestnuts in North Carolina 7 

Conclusions 9 

Department Bulletin 90. — The Rose Aphis: 

Introduction 1 

Recent records 1 

Description 2 

Distribution 4 

Character of injury 4 

Habits 5 

Life history and reproduction in California 5 

Life history and reproduction in the greenhouse 8 

Life cycle in California 9 

Natural control 9 

Experiments with remedies 12 

Department Bulletin 91. — Cost and Methods of Clearing Land in the 
Lake States: 

Introduction 1 

Methods of clearing 5 

Cost of clearing land 10 

Disposal of stumps after pulling 23 

Summary and suggestions 24 

Department Bulletin 92. — Destruction of Germs of Infectious Bee 
Diseases in Heating: 

Introduction 1 

Diseases of the brood of bees 2 

Diseases of adult bees 5 

. Summary and general remarks 8 

Department Bulletin 93. — The Temperature of the Honey-bee Cluster: 

Introduction 1 

The influence of external temperature on heat production 3 

The effect of confinement and the accumulation of feces 6 

Methods of heat production and conservation 13 



CONTENTS. 7 

Department Bulletin 94. — Domestic Breeds of Sheep in America: Page. 

Introduction 1 

Classification of the breeds 4 

The Merino 6 

The Rambouillet 10 

The Southdown 13 

The Shropshire 16 

The Hampshire 19 

The Oxford Down 22 

The Dorset Horn 24 

Suffolk Down 26 

The Cheviot 28 

The Tunis 30 

The Welsh Mountain 33 

The Exmoor horn sheep 34 

TheRyeland 35 

The Kerry Hill 36 

The Lonk 38 

The Shetland 38 

The Leicester 39 

The Cotswold 42 

The Lincoln 45 

The Kent or Romney Marsh 47 

The Wensleydale 49 

The Dartmoor 50 

The Black-fac ed Highland 51 

The Karakule or Arabi 53 

The Persian sheep 55 

The Barbados... 55 

The Barbary sheep or Aoudad 56 

Appendix 57 

Partial index of recent publications on the breeds of sheep 59 

Department Bulletin 95. — Insect Damage to the Cones and Seeds of 
Pacific Coast Conifers: 

Introduction 1 

Character and cause of damage 2 

Important groups of seed-infesting insects 4 

Adaptation of the insects to the intermittent cone-producing habits of the 

host trees 5 

Indications of insect damage 6 

Methods of preventing losses 6 

Department Bulletin 96. — The Temperature of the Bee Colony: 

Introduction 1 

Apparatus 1 

The bees 5 

The arrangement of the thermometers 5 

Location of apparatus , . . . 5 

Check colony 5 

Methods of observation and recording 6 

The consumption of stores in winter : 6 

General phenomena of the cluster in winter 10 

Temperatme below frames in relation to outside air 12 

Comparisons of temperatures of the center of the cluster and of the outside 

air 14 

Effects of manipulation on the cluster 15 

Behavior of the cluster in winter; observations on the check colony 16 



8 DEPARTMENT OF AGRICULTURE, BULLS. 76-100. 

Department Bulletin 96. — The Temperature of the Bee Colony — Con. p age . 

Temperature accompanying the laying of the first eggs 18 

Transition from winter to summer conditions 19 

General phenomena of the summer temperature 20 

Relation of C to the outside temperature 21 

The maxima and minima of C in relation to O 21 

Fluctuations in the hive temperature and the causes 22 

The effect of "Orientation" or "Play flights" 22 

Effects of cluster heat on the temperature below the frames 23 

The effects of storms '. 24 

The effects of transportation on the temperature of the colony 26 

Department Bulletin 97. — Identification of Commercial Fertilizer Ma- 
terials: 

Introduction 1 

Equipment 2 

Isotropic substances : 3 

Anisotropic substances 4 

Uniaxial substances 6 

Biaxial substances 7 

Optical constants of fertilizer materials 10 

Department Bulletin 98. — The Application of Refrigeration to the 
Handling of Milk: 

Introduction 1 

Definition of terms 2 

Changes in milk caused by temperature and time 3 

Methods of utilizing refrigeration 41 

Insulation 49 

Estimating the size of refrigerating plants 57 

Approximate cost of producing mechanical refrigeration in small plants. . . 59 

Requirements of refrigerating plants for dairy purposes 63 

Cooling milk on the farm 65 

Maintaining low temperatures during transportation 69 

Cooling milk at receiving stations 72 

Cooling milk in bottling plants 74 

Refrigeration in creameries 78 

Department Bulletin 99. — Tests of Selections from Hybrids and Com- 
mercial Varieties of Oats: 

Introduction 1 

Parentage of the selections 2 

The sv stem of numbering 3 

Making the selections 4 

Tests at McLean 4 

Tests at the Iowa Agricultural Experiment Station 7 

Tests at the Cornell University Agricultural Experiment Station 11 

Tests at various other experiment stations 18 

Summary 24 

Department Bulletin 100. — Walnut Aphides in California: 

Introduction 1 

The European walnut aphis (Chromaphis juglandicola Kaltenbach) 2 

The American walnut aphis (Monellia caryae Monelli) 19 

The little hickoxy aphis ('Monellia caryella Fitch) 26 

Monellia calif ornica Essig 34 

Naturol control of walnut aphides 35 

Artificial control of walnut aphides 40 

Summary 46 




BULLETIN OF THE 



in 



No. 76 

Contribution from the Bureau of Animal Industry, A. D. Melvin, Chief 
April 29, 1914. 

(PROFESSIONAL PAPER.) 




LABORATORY AND FIELD ASSAY OF ARSENICAL 
DIPPING FLUIDS. 1 

By Robert M. Chapin, 
Senior Biochemist, Biochemic Division. 

INTRODUCTION. 

The use of arsenical dipping fluids for the treatment of cattle 
infested with Texas-fever ticks is increasing. A mixture termed by 
the Bureau of Animal Industry "standard arsenical solution" is pre- 
pared from white arsenic, sal soda, and pine tar, and is largely used 
for both official and private dipping operations. Proprietary dipping- 
fluids also have appeared on the market to some extent. Previous 
publications 2 of the bureau contain directions for the preparation of 
"standard arsenical solution," together with general information of 
importance to users of arsenical dips. 

During the last few years wide practical experience of the bureau 
with all kinds of arsenical dips in the field has shown with increasing 
forcefulness that one of the greatest obstacles to the successful use of 
these preparations, and consequently to the effective prosecution of 
the tick-eradication work now progressing so well over considerable 
areas, lies in the uncertainty attached in many cases to the composi- 
tion of these dips. There is no doubt that arsenical baths, properly 
prepared and used, are very effective tickicides and cause little 
injury to cattle. But the Texas-fever tick is a resistant organism. 
Destruction only follows its immersion in rather strong solutions of 
arsenious oxid, so strong in fact that if made only a little stronger 
the cattle themselves will begin to show effects. That is, the margin 
of safety within which solutions of this violent poison may be satis- 
factorily used is rather narrow. Too little fails to kill the ticks; too 
much injures the cattle. In either case the cause of tick eradication 

1 A popular account of laboratory tests for actual arsenious oxid and for total arsenic, together with 
methods of field assay for dips used in tick eradication. Of special application to officials and others con- 
cerned with the analysis and control of these preparations. 

2 Farmers' Bulletin 498; Bureau Animal Industry Circular 207. 

29207°— 14 1 



2 BULLETIN 76, U. S. DEPARTMENT OE AGRICULTURE. 

receives a setback, not only through the wasted labor of ineffective 
dippings or the economic loss of injured cattle, but still more through 
the arousing of distrust or even enmity in those very persons whose 
willing cooperation in tick -eradication work is most to be desired. 

The causes which may lead to the use of a bath of the wrong 
strength are rather numerous. Impure materials may be purchased; 
mistakes in measurements or computations are sometimes made even 
by a careful man. But these things can all be checked and guarded 
against; the greatest difficulties arise in maintaining the bath at the 
right strength, once it has been prepared. A fresh bath can not be 
made up every time a few cattle are to be dipped. Practical con- 
siderations render it necessary to use the bath over and over again, 
perhaps during a period of several months, sufficient fresh fluid 
being added from time to time to replace that carried out by the 
cattle. During such a period of time, especially in the hot summer 
weather, evaporation of water from the dip naturally tends to con- 
centrate it. This may be compensated for in a measure by marking 
the level of the dip on the side of the vat before a period of disuse, 
and then filling up to the mark with water when the dip is used 
again. But it is difficult to construct a vat holding one to three 
thousand gallons so as to be entirely free from leaks. Therefore it is 
uncertain in any case how much of the lowering of the level of the 
dip is attributable to evaporation and how much to leakage. Leakage 
may likewise be in as well as out; that is, rain, surface water, or 
ground water may enter the vat. 

Even if these difficulties are avoided, there is still another factor 
which evades all precautions, the fact that used arsenical dipping 
fluids may in course of time undergo a process of oxidation whereby 
the arsenious oxid originally present as sodium arsenite is converted 
to arsenic acid or sodium arsenate. Various observers have noted 
such a tendency, but have usually attached little importance thereto, 
assuming it to be caused by a slow and relatively insignificant 
chemical reaction. It has remained for Fuller, 1 working in this 
laboratory, to show that the change is essentially caused by the 
growth of microorganisms in the fluid— that is, it is a biological 
process and not a simple chemical action — and furthermore that it 
may become very extensive, converting nearly all the arsenic into 
the oxidized form. Tests by the Zoological Division of the bureau 
indicate that arsenic in the form of arsenate is probably a less effective 
tickicide than when present as arsenite, while at the same time 
decidedly poisonous to animals. Laws, 2 as the result of a certain 
number of experiments, has concluded that arsenic, existing as arse- 

1 Bureau Animal Industry Circular 182. 

2 Laws. The Tick-killing Properties of Sodium Arsenate. The Agricultural Journal of the Union of 
South Africa, 1913, vol. 5, p. 915. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 6 

nate is probably somewhat less than half as powerful as arsenic in 
the form of arsenite in its effects upon both cattle and ticks. Also 
it has recently been observed that arsenical baths under certain con- 
ditions sometimes display the converse phenomenon of reduction — 
that is, arsenate tends to be reconverted to arsenite. Laws, in the 
article above mentioned, suggests that the phenomenon of reduction 
may likewise be attributable to the action of microorganisms, of 
course of different species from the organisms which cause oxidation. 
Recent work in this laboratory has substantiated the correctness of 
Laws's surmise. Pending the completion of certain researches it may 
simply be stated here that both phenomena have been observed to 
occur in baths in actual use in the field, sometimes in the same bath; 
that is, a single bath may show alternating tendencies in the two 
directions, first toward oxidation, then toward reduction followed by 
oxidation again, and so on. The primary condition which determines 
in which direction the change shall progress at any given time or in 
any particular bath is the degree of use which the bath is receiving. 
Under present ordinary conditions which appear to prevail in the 
field a gradual oxidation may be looked for. It is only in vats 
through which cattle are passed in exceptionally large numbers and 
at very frequent intervals, such as the vats at some of the stockyards 
centers, that reduction as a separate phenomenon becomes apparent. 

A consideration of the above facts renders sufficiently obvious the 
necessity for some analytical control of the baths used for dipping. 

The assay of arsenical dipping fluids, at least with sufficient 
accuracy for practical purposes, is not a difficult matter. It is no- 
where described in chemical literature, however, and the average 
chemist, when offered the problem, will be somewhat daunted, not 
knowing how he may best set to work to obtain good results without 
a considerable expenditure of labor. It is believed that some of the 
methods herein to be described can be successfully executed by per- 
sons who possess but a limited chemical training. In almost every 
section of the country there should be some one, pharmacist, physician, 
veterinarian, instructor in school or college, or even student, who 
would find it worth while for a comparatively small fee (provided a 
sufficient number of samples are sent in from various sources) to 
undertake the assay of such preparations. A 4-ounce sample * is 
sufficient, though a larger quantity is rather more convenient for the 
analyst. 

It is also purposed to describe a portable testing outfit that has 
been devised for the use of bureau inspectors in the field, and that 
enables them, without the possession of any chemical knowledge 
whatever, at the side of the vat and in a few minutes, to determine 

1 For precautions necessary in sending samples see page 4. 



4 BULLETIN 76, U. S. DEPARTMENT OF AGRICULTURE. 

the strength of arsenical solutions prepared after the ''standard 
formula." 

It is necessary therefore to describe (1) methods for the determina- 
tion of actual arsenious oxid, and (2) methods for the determination 
of " total arsenic/' that is, methods which shall include arsenic 
present in the oxidized form as well as that existing as actual arse- 
nious oxid. It is necessary also to describe different variations or 
modifications of processes for these two determinations, respectively 
appropriate for use by (1) trained chemists with abundant laboratory 
facilities, (2) persons possessing but slight chemical training and 
equipment, and (3) persons in the field possessing no chemical 
knowledge or training whatever, who obtain their results by manipula- 
tion of an "outfit" prepared by a trained chemist. 

LABORATORY METHODS. 

It is to be distinctly understood that the methods here described 
are not in all cases adapted or intended to reach a high degree of 
accuracy from a chemist's viewpoint, though as a matter of fact 
most of them are very accurate under especially favorable conditions. 
A certain variation must necessarily be allowed in the composition 
of baths prepared in the field. Again, experience has shown that the 
percentage of arsenic in such baths may vary within certain limits 
without perceptible effect upon either their effectiveness or their 
safety. Therefore the purpose of assay is not primarily to determine 
the exact percentage of arsenic — though the nearer this result is ap- 
proached the better — but to insure that the composition of the baths 
used shall fall within certain limits. Extreme accuracy, which is not 
necessary, must be sacrificed to simplicity and convenience, which 
are necesssary to permit the execution of very frequent tests. 

METHODS FOR ACTUAL ARSENIOUS OXID. 

Whatever method may be employed for the determination of actual 
arsenious oxid, there are certain precautions connected with the tak- 
ing and the storage of samples which can not be omitted if the results 
are to be of any value whatever. As already noted, the arsenic in 
used arsenical baths tends to change its degree of oxidation, 
mainly through the action of microorganisms. Other tilings being 
equal, the rapidity with which this change takes place is greatly 
influenced by temperature, so much so that a sample contained in an 
ordinary cork-stoppered bottle and exposed to summer heat may show 
more change after one day than it would show after a week in the 
original vat in its comparatively cool location underground. The rate 
of the change can accordingly be retarded by keeping the sample cold, 
as by storage in an ice box after receipt; but if the sample has trav- 



ASSAY OP ARSENICAL DIPPING FLUIDS. 5 

eled any considerable distance the mischief probably has already been 
done before its receipt. The growth of microorganisms, and conse- 
quently the change in degree of oxidation, can be inhibited by the 
addition of an appropriate antiseptic, such as formaldehyde, care- 
fully added from a medicine dropper, in the proportion of 5 drops 
of the commercial 37 per cent solution to each 100 c. c. of bath. 
Carbolic acid and mercuric chlorid are wholly inappropriate for the 
purpose. Also since oxidation obviously can not take place in the 
absence of air, it is best to fill the bottle nearly full with the sample, 
leaving only a little air space, cork, and cover the cork and lip of 
bottle (which must be dry) completely with melted sealing wax, 
paraffin, rosin, or some similar material. Whatever means are 
employed to preserve the sample the operations ought to be executed 
at the vat side immediately after taking the sample. A few matches 
will furnish the heat necessary for melting the sealing material. 

No sample should, of course, be taken from a vat until the contents 
of the latter have been thoroughly stirred up. Aside from general 
reasons for this practice in all sampling it is entirely possible that the 
oxidation of an arsenical bath standing at rest in the vat may proceed 
from the surface downward. That is, the upper few inches in free 
contact with air might have become almost entirely oxidized while 
toward the bottom the bath might be still in its original condition, 
or might even be undergoing reduction. 

The first step for the analyst, therefore, is to determine whether the 
sample has been properly taken and properly preserved during 
shipment. If the necessary preacutions have not been observed, 
the analyst is justified in reporting only a "probable" or "provis- 
ional" figure for "actual arsenious oxid." 

The final measurement of arsenic is made in all cases by titration 
with standard iodin solution and starch indicator, much used by 
chemists for a variety of purposes. The necessary solutions are the 
following : 

(1) Starch solution. — Stir up about a gram of starch, best obtained 
from the druggist, in about 20 c. c. of water and add the mixture 
slowly to about 200 c. c. of boiling water. Continue gentle boiling 
about 5 minutes. The solution should be freshly prepared every 
day. 

(2) Diluted sulphuric acid (10 per cent). — Pour 100 grams (or 
55 c. c.) of concentrated sulphuric acid slowly, in a small stream and 
unth constant stirring, into 825 c. c. of water. 

(3) Standard solution of arsenious oxid. — Weigh out accurately 
and exactly 2.5 grams of the purest obtainable white arsenic, and 
about 10 grams of sodium bicarbonate, bring into a capacious beaker 
or flask with about 200 c. c. of water, and boil gently until the arsenic 
is all dissolved. Cool, and cautiously add dilute hydrochloric or 



6 BULLETIN 76, U. S. DEPARTMENT OF AGRICULTURE. 

sulphuric acid until the solution is slightly acid to litmus paper or 
methyl orange, or, best of all, phenolphthalein. When thoroughly 
cooled to room temperature, make up the solution to exactly 1,000 
c. c. Each cubic centimeter will then contain 0.0025 gram arse- 
nious oxid. The chemist 1 will recognize this as approximately 
a "twentieth-normal" solution. If well stoppered, the solution 
will keep a year or more. 

(4) Standard iodin solution. — Weigh out about 6.5 grams of iodin 
and 20 grams of potassium iodid. Cover with about 100 c. c. of water 
and leave, occasionally mixing, until all iodin is dissolved. Then 
make up to 1 liter. To obtain the exact strength of the iodin solution, 
measure exactly 25 c. c. of the standard arsenious oxid solution into 
a 200 c. c. flask or wide-mouth bottle, add about 25 c. c. of water, 
about 2 grams of sodium bicarbonate, and a few cubic centimeters of 
starch solution. Then, while shaking the flask, run in the solution 
of iodin from a burette 2 until the blue color of iodized starch just 
remains permanent. Twenty-five cubic centimeters of the standard 
arsenious oxid solution contain exactly 0.0625 gram of arsenious oxid. 
Therefore, the number 0.0625 divided by the number of cubic centi- 
meters of iodin solution necessary to just produce a permanent blue 
color, gives a quotient which represents the exact weight of arsenious 
oxid to which each cubic centimeter of iodin solution is equivalent. 
For example, suppose 26.2 c. c. of iodin to be required. Then 
0.0625^-26.2 = 0.00239 gram arsenious oxid per each cubic centime- 
ter of iodin. The standard iodin solution should be kept only in glass- 
stoppered bottles, as it will be weakened by contact with rubber or 
cork. If preserved in tightly stoppered and well-filled bottles in a 
cool, dark place, it retains its strength a considerable time, but in 
practice it should be standardized against the standard solution of 
arsenious oxid every week or two. 

For the actual analysis two methods will be described. If the 
sample is a concentrated preparation, it should always be reduced 
by dilution with water to the strength at which it is intended for use 
in actual dipping. 

METHOD "A" FOR ACTUAL ARSENIOUS OXID. 

Measure 25 c. c. of bath into a beaker, flask, or bottle of convenient 
size, add about a gram of sodium bicarbonate and about 10 c. c. of 
starch solution. Run in standard iodin solution until the blue color 
appears just as in standardizing the iodin solution, though here it 

i The experienced chemist will undoubtedly employ solutions of definite normality. The directions 
here given are intended, as simply as possible, to meet the needs of those who may be without much 
chemical knowledge or a highly accurate analytical balance, perhaps lacking even burettes and pipettes. 

*A 25 c. c. measuring cylinder may be employed if a burette is lacking. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 7 

usually fades out in a minute. In the case of very dirty baths the 
color may appear simply as a violet, reddish, or brownish deepening 
of the naturally dark color of the bath itself. In such cases it is 
well to have two flasks at hand, both containing the measured por- 
tions of bath and starch solution. Then by running iodin solution 
into one of the flasks and constantly comparing the color with the 
color of the liquid in the other flask, the point at which the change 
occurs may be more easily distinguished. Since the color is not at 
all permanent in the case of old and dirty baths, and since slight 
changes of tint are impossible to distinguish in such baths, it is good 
practice to add the iodin solution in quantities of 0.5 c. c. at a time 
when it is suspected that the end point is close at hand, then to mix 
thoroughly and immediately observe the color. This quantity of 
iodin solution is usually sufficient to produce a very pronounced 
change of tint if the end point of the titration really has been reached. 
The final reading should then be corrected by subtracting 0.25 or 
0.50 c. c, whichever is judged nearest correct. The number of cubic 
centimeters of iodin solution needed to produce the blue color, 
multiplied by the strength of each cubic centimeter in terms of 
arsenic, and this again by 4, will give the grams of arsenic per 100 c. c. 
of bath — that is, the percentage. For instance, suppose that each 
cubic centimeter of iodin solution was found to be equivalent to 
0.00239 gram arsenious oxid, and that 18.3 c. c. of iodin solution were 
employed in the titration of 25 c. c. of a bath under examination. 
Then the bath contains 0.00239X18.3X4 = 0.175 per cent of actual 
arsenious oxid. 

Theoretically, method "A" can not be applied with perfect accu- 
racy to dipping baths, on account of the possibility that substances 
other than arsenious oxid — such as tar and organic matter derived 
from the cattle — may absorb some iodin and thus lead to false results. 
Practically, however, this method has been shown by many tests to 
give useful results on dipping baths of all ages prepared after the 
"standard formula" recommended by the Bureau of Animal Indus- 
try. (See p. 1.) That is, the various ingredients of the tar and the 
organic matter derived from cattle actually do not interfere fatally, 
but absorb iodin so slowly that the end point with starch is obtainable 
without difficulty, although it usually fades out in a brief time. 
Therefore, method "A" is suggested for use in the practical testing 
for ordinary purposes of baths prepared after the "standard formula." 
It must not, however, be employed on baths prepared from any 
proprietary dip unless it is certainly known that the particular dip 
contains no substance which can interfere. Since it is the present 
policy of the bureau to permit for use in official dipping only such 
proprietary preparations as may be satisfactorily tested by means of 
the field outfit later to be described, and since the field test is practi- 



8 BULLETIN 76, U. S. DEPARTMENT OE AGRICULTURE. 

cally identical with method "A," the latter method may be safely 
employed for the examination of samples known to be prepared 
from proprietary dips which have received such oflicial recognition. 

METHOD "b" FOR ACTUAL ARSENIOUS OXID. 

Measure 25 c. c. of bath into a small beaker, add 5 c. c. of 10 per- 
cent sulphuric acid and 0.25 gram of acid- washed blood-charcoal. 
Stir thoroughly and heat nearly to boiling — best on a steam bath — for 
five minutes. Then filter and wash with hot water until the filtrate 
amounts to a little over 100 c. c. If the bath appears to be very 
heavily loaded with dirt or tar, the addition of about a gram of acid- 
washed kieselguhr (infusorial, siliceous, or diatomaceous earth), 
followed by thorough stirring before filtration, will greatly hasten 
the passage of the liquid through the filter. When the filtrate has 
been thoroughly cooled to room temperature, sodium bicarbonate 
is added until 1 or 2 grams are present in excess after effervescence 
ceases. In case the bath was prepared from a proprietary product, 
dilute to about 200 c. c. before adding sodium bicarbonate, and 
lastly also add 2 grams potassium iodid. 1 Finally, the solution is 
titrated with standard iodin and the result calculated as under 
method " A." If the greatest possible accuracy is desired a correction 
must be made for loss of arsenic through the use of blood-charcoal. 
This substance notably adsorbs arsenious oxid, and even after 
thorough washing a slight amount remains unaccounted for, which 
presumably still is retained by the charcoal. The amount of arsenic 
so lost appears — at least within practical limits — to be independent 
of the concentration of the bath, but is naturally dependent upon 
the amount of charcoal employed. Hence the charcoal must be rather 
carefully weighed or measured, and the amount of the correction for 
each lot of charcoal must be established by running comparative 
titrations on two portions of a solution of pure arsenious oxid, one 
direct, the other after the treatment with charcoal, filtration, and 
washing, which has been described. 2 The power of the charcoal to 
produce a water-white filtrate in which the blue end point is sharp 
and permanent far outweighs its disadvantages if accurate results 
arc desired. 

Method "B," like method "A," should not be applied to proprie- 
tary dips unless they are permitted for use in official dipping or are 
otherwise known to be free from interfering substances. 

1 Dilution and the addition of potassium iodid aids in nullifying the interfering effect of cresylic acid and 
other substances capable of absorbing iodin which may be present in proprietary dips. Phenols rapidly 
a bsorb iodin from a solution containing sodium bicarbonate. The presence of free carbonic acid, which of 
course saturates the liquid during titration, greatly reduces the rate of absorption. Finally, if the solution 
contains a certain concentration of potassium iodid, and not above a certain concentration of the phenols, 
the end point comes out perfectly sharp, of good color and permanency, following a titration figure which 
ars wholly unafTected by the presence of phenols. 

1 The sample of blood-charcoal at present in use in this laboratory demands a correction of 0.2 c. c. of 
twentieth-normal iodin for 0.25 gram charcoal. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 9 

METHOD FOR " TOTAL ARSENIC." 

Strictly speaking the oxidized form of arsenic no longer contains 
arsenious oxid as such (As 2 3 ) but only arsenic oxid (As 2 5 ). Never- 
theless, for the purpose of making simple and convenient compari- 
sons, it is necessary to refer all quantitative statements regarding 
arsenic compounds to the common basis of their equivalent in arseni- 
ous oxid. Therefore, the term "total arsenic" is employed to signify 
all arsenic present in any form of combination or degree of oxidation, 
expressed in terms of arsenious oxid. 

The method to be described is a standard method based on the 
well-known fact that the reaction As 2 3 + 41 + 2H 2 0;zAs 2 5 -f- 4HI is 
reversible, going from left to right in neutral or alkaline solutions, 
and from right to left in solutions which are freely acidified with a 
strong mineral acid. The reaction from left to right is the basis for 
the previously described methods for the determination of actual 
arsenious oxid. To determine total arsenic it is only necessary to 
allow the reaction to progress to completion from right to left, then 
to determine the resulting arsenious oxid in a manner similar to that 
already described. 

The solutions and reagents necessary, in addition to the same stand- 
ard iodin solution, starch solution, dilute sulphuric acid, and solid 
sodium bicarbonate, are anhydrous powdered sodium carbonate, solid 
potassium iodid, a one- tenth per cent solution of methyl orange, 
possibly concentrated sulphuric acid, and lastly a solution of sodium 
thiosulphate containing about 25 grams per liter. 

The first step is to clarify and decolorize the solution. Hence 
proceed exactly as in method "B" for actual arsenious oxid (p. 8) 
until the filtered solution has been obtained. When both actual and 
total arsenious oxid are to be determined it is most convenient to 
double the quantities of both acid and charcoal, and to filter into a 
200 c. c. volumetric flask. After thorough washing and cooling, the 
contents of the flask are made to the mark, mixed, and divided into 
two equal portions, one for actual arsenious oxid, the other for total 
arsenic. In either case transfer the solution containing the equiva- 
lent of 25 c. c. of the original bath to a 200 c. c. beaker, add 4 c. c. 
of concentrated sulphuric acid and about 2 grams of potassium 
iodid, boil gently until the volume of liquid is reduced to 50 c. c, then 
cool to room temperature. The next step is to remove free iodin from 
the solution. This may be done while the solution is still in the 
beaker, by adding the solution of sodium thiosulphate drop by drop 
from a burette until the yellow color of free iodin just disappears. 
Any excess of thiosulphate must be carefully avoided. A safer 
procedure for one not experienced with the method is to wash the 
contents of the beaker into a flask of 600 to 800 c.c. capacity, dilute 

29207°— 14 2 



10 BULLETIN 76. U. S. DEPARTMENT OF AGRICULTURE. 

to about 200 c. c, nearly discharge the color of iodin by sodium 
thiosulphate, add a little starch solution, and continue the cautious 
addition of thiosulphate solution until the blue color disappears. 
Then add standard iodin solution from a burette until the faintest 
possible persistent blue remains. Whichever method is used, the 
solution at this stage should be in a capacious flask, and should be 
diluted to about 300 c. c. Add a few drops of methyl orange, then 
render alkaline by the cautious addition with a spatula of anhydrous 
sodium carbonate. When the solution is clearly alkaline wash down 
any solid adhering to the neck or sides of the flask and add dilute 
sulphuric acid until the reaction is clearly acid, taking care that no 
particles of sodium carbonate remain undissolved. Then add a 
liberal excess of sodium bicarbonate, 10 c. c. more starch solution, 
and titrate with standard iodin in the usual manner. -The final 
titration should of course be corrected for the adsorption of arsenious 
oxid by blood-charcoal. No additional correction for adsorption of 
arsenic oxid appears necessary. No extra addition of potassium 
iodid appears to be necessary in case cresylic acid, etc., is present. 

The above-described methods for actual arsenious oxid and for total 
arsenic have proved reliable for the examination of all products thus 
far permitted for use in official dipping, and it is probable that they 
will be found applicable to any proprietary products which may 
receive such official recognition in the future, though obviously a 
positive statement on this point can not be made. The experienced 
chemist will naturally think of other methods which might be applied. 
For example, the acidified and filtered bath may be treated in a sepa- 
rating funnel with ether or some other appropriate organic solvent 
to extract cresylic acid, fatty acids, etc.; total arsenic may be deter- 
mined after the destruction of organic matter by appropriate diges- 
tion or incineration, or it may be separated by distillation; while it is 
known that some chemists prefer to determine directly arsenic 
existing as arsenic acid by titration with uranium acetate. 

FIELD METHODS OF ASSAY. 

A field method of assay is generally based upon a laboratory 
method; apparatus, reagents, etc., being simplified to the extreme 
in the interests of durability and portability, and the operations 
being reduced to the fewest and simplest, that they may be success- 
fully executed by persons wholly unacquainted with chemistry as a 
science. But a skilled chemist in the laboratory to supervise the 
iicld tests is even more necessary than if all the work were actually 
performed in the laboratory itself, for upon his experience and care 
reliance must be placed to standardize the methods in such a way 
that useful data may actually result from the manipulation of inade- 
quate apparatus by unskilled hands. Of course, it is only excep- 



ASSAY OF ARSENICAL DIPPING FLUIDS. 11 

tionally that a laboratory method can be modified so that it is of 
any practical use whatever in the field, and in any event it is almost 
certain to lose something in accuracy. One thing is absolutely 
essential, that the field operator shall follow the instructions given 
him to the minutest detail, no matter how irrelevant or unimportant 
they may appear to him. 

FIELD METHOD FOR ACTUAL ARSENIOUS OXID. 

The field method at present employed by the bureau for actual 
arsenious oxid is simply an adaptation of laboratory method "A" 
for the same substance. The outfit is pictured in figure 1, and each 
part composing it will be described in detail. 

(1) The case. — The carrying case for the outfit is a rectangular box 
with a hinged cover, made of five-sixteenths-inch oak, of inside dimen- 
sions 1\ by 5 J by If inches. The interior partitions, of thinner and 
softer wood, are sufficiently indicated in the diagram. The case 
must be strongly mortised or nailed together, not simply glued, and 
should be varnished inside and out. 

(2) The utensils. — Bottle A', fitting into compartment A of the 
case, is an ordinary 3-ounce wide-mouth bottle of clear glass. 

Measuring cylinder C, fitting in compartment C, is of ordinary 
type, of 25 c. c. size, graduated to half cubic centimeters. Preferably 
the figures indicating the graduations read down only. C" is a bristle 
swab for cleaning. It will be noted that the partitions of compart- 
ment C are cut away at the bottom to admit the foot of the cylinder. 
At the point p on the back wall of the case is fastened a quarter-inch 
pad of cork to protect the cylinder from breakage. The swab C" is 
put into compartment C after the cylinder, thus protecting the latter 
from breakage on that side. 

(3) The reagents. — The iodin solution, or, as it is termed for field 
use, the "test fluid," is contained in bottle D', a 4-ounce standard- 
shaped " sample oil" bottle, preferably of amber glass and provided 
with a "flat-hood" glass stopper. A half -inch ring of the If -inch 
(measured flat) thin rubber tubing, manufactured for use with Gooch 
crucibles, is drawn over the shoulder of the bottle, cemented in place, 
and coated with collodion. At the bottom of compartment D is 
fastened by a screw a conical spiral spring, the upper whorl of which 
is large enough to inclose the bottom of the bottle. In placing the 
latter in the case the bottom is inserted in the whorl of the spring 
and the bottle then pressed down until it slides into place. The 
partition between C and D is cut away in a semicircle at the point # 
to allow the fingers easy access to the bottle when it is to be removed. 

The test fluid is of such strength that in the actual performance 
of the test each cubic centimeter of it employed represents exactly one 



12 BULLETIN 76, U. S. DEPARTMENT OF AGRICULTURE. 







w 



o 



^ 



x#* 



/*— >^< /, 



Oi 



^? 




^ 



^ 








Fig. 1.— Test outfit for arsenic baths. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 13 

one-hundredth of 1 percent of arsenious oxid in the bath under test. 
Therefore its strength should be originally fixed by standardizing it 
with the field apparatus against an average sample of used bath from 
the field in which the percentage (adjusted if necessary by the addi- 
tion of a little concentrated solution of arsenious oxid in sodium car- 
bonate) of actual arsenious oxid is close to 0.20 per cent and is accu- 
rately known through laboratory analysis. The true strength of this 
empirically standardized iodin solution should then be ascertained by 
titration against a strictly tenth-normal or twentieth-normal solution 
of arsenious oxid, and the result obtained may thereafter serve as the 
basis for the preparation of subsequent lots of test fluid. Obviously 
the true strength of the iodin solution will be influenced to some extent 
by the method of graduation of the cylinder, whether graduated "to 
contain" or "to deliver," and also by the depth of the meniscus, 
which in turn is influenced by the diameter of the cylinder. Hence, 
all field outfits under the supervision of a single laboratory should be 
fitted with cylinders of uniform model. Reserve supplies of test fluid 
should be kept in small, well-filled, tightly closed glass-stoppered 
bottles, and in a cool, dark place. 

In addition to the test fluid, starch and sodium bicarbonate, or 
some equivalent substance, are of course necessary. In fact, the 
practical preparation of a satisfactory form of starch has been 
the greatest difficulty attached to the whole process, though at the 
same time the key to its success. 

It has been known for many years that by the use of alcohol starch 
may be precipitated in water-soluble form, also that high-percentage, 
yet mobile, starch solutions may be obtained through proper treat- 
ment with hydrochloric acid, but the working out of a practical 
process for the preparation in quantity of a dry starch readily soluble 
in cold water and appropriate for use as an indicator appears not to 
be recorded. 

Into a 5-liter round flask with a long neck is brought 400 grams potato 
starch, 2,300 c. c. distilled water, and, lastly, 80 c. c. of normal hydro- 
chloric acid. The flask is well shaken to thoroughly wet and distrib- 
ute the starch and is floated in a kettle of water previously brought 
to vigorous boiling. The neck of the flask conveniently rests on the 
side of the kettle at an angle of about 45°, and as soon as the 
flask is brought into the bath it is gently but continuously rotated 
about its longitudinal axis. As the flask becomes hot the starch 
forms an evenly distributed, uniform jelly, which in about 7 minutes 
from the time of starting begins to liquefy and to fall away from the 
wall of the flask. When this stage is reached the mouth of the flask 
is loosely closed with an inverted beaker and the flask left in the boil- 
ing bath with an occasional rotation until the liquid becomes mobile 



14 BULLETIN 76, U. S. DEPARTMENT OF AGRICULTURE. 

and shows no lumps of gelatinized starch remaining, which should 
take a little over an hour. The flask is quickly cooled in running 
water until it can be comfortably handled, then a few drops of methyl 
orange are added, followed by concentrated ammonia to alkaline reac- 
tion. Next is added 800 c. c. of 95 per cent alcohol with thorough 
mixing, and after a few minutes standing to allow air bubbles to sepa- 
rate, the liquid is strained through moderately coarse muslin. The 
addition of this amount of alcohol is insufficient to permanently pre- 
cipitate any starch, but notably thins out the original aqueous solu- 
tion. Starch will separate some time after the solution has become 
cold, but with proper management ample time remains for the subse- 
quent necessary operations. The solution, still at 40° to 45° C, is 
run through a number of fine jets into 4,000 c. c. of 95 per cent alco- 
hol, under continuous stirring. The whole is left for at least 48 
hours with an occasional thorough stirring, after which most of 
the supernatant alcohol is decanted, and the rest used to transfer the 
starch to a 2-quart narrow percolator provided with a filter plate 
which is covered with filter paper or cloth. Here it is percolated 
with 95 per cent alcohol, being stirred up with a stick at intervals to 
prevent the formation of clumps or fissures, until the alcohol comes 
through of a specific gravity indicating a strength of 90 per cent. 
The starch is then transferred to a Buchner funnel, well drained with 
suction, and then spread out to dry in a moderately warm place.' 
The starch so prepared is a fine white powder, more or less compacted 
to friable lumps, which completely disintegrate under slight pressure. 
A little of it thrown into cold water in less than a minute dissolves 
sufficiently to yield a good blue upon the addition of iodin and potas- 
sium iodid. Moistened with water or diluted alcohol it becomes 
gummy and dries out to a horny mass, difficultly soluble in cold water. 
The efficiency of the preparation therefore is dependent upon its 
fine state of subdivision, and care must be taken during the process not 
to expose it to air until after thorough digestion with alcohol of 90 per 
cent strength. It should be passed through a 60 or 80 mesh sieve 
and protected from moist air. 

The soluble starch may be thoroughly mixed with 10 times its 
weight of powdered sodium bicarbonate and the mixture divided into 
powders of about 0.6 gram, which may be packed in a j>aste- 
board box fitting into compartment B of the case. On the large 
scale, however, it is much better to make the mixture up into tablets, 1 
after the following formula : 

1 It is something of an art to make good tablets. No one should attempt it until thoroughly conversant 
with the principles of the process, and then only on a small scale until experience is gained. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 



15 



Milk sugar in fine powder grams . . 100 

Sodium bicarbonate, in powder do 1, 000 

Mix, moisten with dilute alcohol, granulate, dry thoroughly at only 
slightly elevated temperature, and grind granules to pass a 20-mesh 
sieve. 

Mix granules with — 

Soluble starch grams. . 100 

Raw potato starch do 75 

Talcum, IT. S. P do. . . . 25 

Compress into tablets of 0.65 gram. 

The practical tablet maker' will be tempted to criticize this formula 
because it carries so much powder; but since the soluble starch is 
ruined by wetting it can not be incorporated into the granules, so 
that there appears to be no escape from this drawback, which at any 
rate has not prevented the practical preparation of the tablets on a 
large scale for the use of the bureau." 

The tablets are put up in the 1 -ounce wide-mouth bottle B', fitting 
into compartment B of the case. 

On the inside of the cover of the case is glued a printed instruction 
sheet, which is protected by pyroxylin varnish. The instructions 
read as follows : 



United States Department op Agriculture, 
Bureau of Animal Industry. 

TEST CASE FOR ARSENICAL BATHS. 

Not to be used on baths prepared from proprietary 
preparations except on special instruction. 

Keep test fluid in a cool dark place iu glass-stoppered 
bottles only. 

directions. 

1. Fill clean graduate with bath, setting the top 
edge of the surface of the bath on the upper gradua- 
tion (zero or 25 c. c), pour (draining out drops) into 
clean wide-mouth bottle, add one white indicator 
tablet, and gently swirl or shake till tablet is nearly 
all dissolved. 

2. Rinse graduate with clean water, shake out ad- 
hering drops (or rinse with a little test fluid), and fill 
to upper graduation (zero) with test fluid, setting the 
bottom of the curved surface on the mark. 

3. While gently swirling bottle, slowly pour in test 
fluid from the graduate until the blue or violet color 
remains permanent for a half minute throughout the 
entire contents of the bottle after thorough mixing. 
Avoid excess of test fluid, adding only a few drops 
at a time toward the end. 

The number of cubic centimeters (reading at the bot- 
tom of the curved surface) of test fluid added to just pro- 
duce the color gives the number of hundredths of 1 per 
cent of arsenious oxid in the bath. 



If the assay is not performed at the vat directly after taking the 
sample, the same precautions to prevent changes in degree of oxida- 
tion must be observed as described under "Laboratory Methods for 
Actual Arsenious Oxid" (p. 4). The scope of application of the 
method is of course subject to exactly the same limits as laboratory 
method "A" for actual arsenious oxid (p. 6). 



16 BULLETIN 76, U. S. DEPARTMENT OF AORICULTUEE. 

FIELD METHOD FOR "TOTAL ARSENIC." 

Since, pending further investigation, it is not possible to credit 
arsenic in the higher form of oxidation (arsenic acid or arsenates) 
with definite value as a tickicide, the efficiency of dipping baths must 
be judged for the present solely on the results afforded by the test 
for actual arsenious oxid. On the other hand, studies of changes in 
the composition of a number of dipping baths in actual service in the 
field, together with practical experience, have so far failed to show a 
clearly defined danger that the average bath, in which the strength 
of actual arsenious oxid is maintained, is likoly to reach a degree of 
oxidation which may render it dangerous to cattle. Nevertheless, in 
view of obvious possibilities in these two directions, it is desirable to 
possess a field method for the estimation of total arsenic. The method 
to be described makes use of a chemical reaction recently discovered 
by the writer, 1 namely, the reduction of arsenic acid to arsenious acid 
by thiosulphuric acid. After reduction and removal of excess thio- 
sulphuric acid by iodin in acid solution, sodium bicarbonate may be 
added and the arsenious oxid, now representing the total arsenic, may 
be titrated in the usual way. The method is necessarily more com- 
plicated, more tedious, and. less accurate than the simple method for 
actual arsenious Oxid. . Nevertheless, rather comprehensive tests by 
representatives of the bureau in the field indicate that, if conditions 
demand such a test and no better can be discovered, the one at hand 
will afford useful results. 

In addition to the outfit and supplies already described, the follow- 
ing supplies are necessary: 

1. "Red tablets": 

Talcum powder, U. S. P grams. . 10 

Haw potato starch do 30 

Mix, and stir in 0.1 gram Sudan Red III dissolved in sufficient ether to distribute 
the color, and evaporate off ether at a moderate temperature with frequent stirring. 
Add: 

Sodium bicarbonate in fine powder grams . . 3 

Special soluble starch do 10 

Mix, and add potassium pyrosulphate powdered to pass a 40-mesh sieve, do 125 

Mix well and compress into tablets of such size that 1 tablet will neutralize 9 to 10 
c. c. of normal alkali. The mixture, not being granulated, can not be run through the 
hopper of a power tablet machine, but must be fed by hand into the die from the table 
of the machine. 

2. "Blue tablets" : 

Ultramarine blue grams. . 1 

Talcum powder, U. S. P do 5 

Sodium thiosulphate, crystallized, ground to pass 20-mesh sieve, and air- 
dried do. ... 100 

Mix and compress into tablets of such size that 1 tablet will be equivalent to about 
22 c. c. of twentieth-normal iodin. 2 

1 Journal of Agricultural Research, 1911, vol. I, p. 515. 

2 It is probable that potassium iodid should also be added in making up these tablets in order to prevent 
some oxidation of arsenious oxid by iodin in acid solution in case "oxidized arsenic" is originally present 
in amount sufficient to nearly completely use up the thiosulphate. 



ASSAY OF ARSENICAL DIPPING FLUIDS. 17 

The directions for executing the test read as follows : 

1. Use regular outfit. Measure 25 c. c. of bath into wide-mouth bottle and add 1 blue 
tablet. When entirely dissolved, add 1 red tablet, and after this has entirely fallen to 
powder gently but continuously swirl the bottle for 3 minutes, then let it stand for 7 
minutes more with an occasional mixing. 

2. Next add test fluid from the graduate until the blue color ju^t remains perma- 
nent for at least 10 seconds throughout the whole of the well-mixed liquid. Add but 
a few drops at a time toward the end and avoid excess, but pay no attention to the 
actual volume of test fluid added at this stage. 

3. Now add two white indicator tablets and agitate till mostly dissolved. Fill the 
graduate to upper mark (zero) with test fluid, adding it just as in the estimation of 
"actual arsenious oxid" until the blue color just reappears permanently, avoiding 
excess. 

The number of cubic centimeters of test fluid thus added to bring back the blue 
color represents hundredths of 1 per cent of "total arsenic" in the bath. 

If "oxidized arsenic" is present in only very small amount the 
results are likely to be somewhat low, owing to some formation of 
arsenious sulphid, but in any event such small amounts of "oxidized 
arsenic" are without significance. Again it is obvious that the 
quantity of thiosulphate used will not show the presence of ' ' oxidized 
arsenic" in amount much over 0.2 per cent of the bath, but this 
appears amply sufficient, for if so much is present, in addition to the 
actual arsenious oxid, which of course is determinable in practically 
any amount, the bath certainly should not be used for dipping. 

THE INTERPRETATION OF RESULTS. 

The "standard arsenical solution" is recommended by the bureau 
for use in two strengths — -first, 10 pounds of white arsenic and 25 
pounds of sal soda to each 500 gallons, and, second, 8 pounds of white 
arsenic and 24 pounds of sal soda to each 500 gallons of bath. The 
theoretical percentages of arsenious oxid will therefore be prac- 
tically 24 hundredths of 1 per cent for the 10-25 formula, and 19 
hundredths of 1 per cent for the 8-24 formula. Practical experience, 
however, has shown that the baths work with perfect satisfaction 
so long as the percentages of "actual arsenious oxid" do not drop 
below the following limits: For the 10-25 formula, 22 hundredths 
of 1 per cent; for the 8-24 formula, 175 thousandths of 1 per cent. 
These figures therefore represent minimum percentages below which 
the contents of the respective baths in "actual arsenious oxid" 
should not be allowed to fall. The maximum allowed percentages 
of "actual arsenious oxid" should be but little above the theoretical 
figures; say, 25 hundredths of 1 per cent for the 10-25 formula and 
20 hundredths of 1 per cent for the 8-24 formula. 

Respecting the maximum allowable percentages of "total arsenic," 
it is not yet possible to make any statements based upon positive 
experimental evidence. One might tentatively set the following 
limits which experience has indicated to be within the margin of 
safety: 30 hundredths of 1 per cent for the 10-25 formula; 25 hun- 
dredths of 1 per cent for the 8-24 formula. 

o 




BULLETIN OF THE 



No. 77 




Contribution from the Forest Service, Henry S. Graves, Forester. 
May 7, 1914. 

(PROFESSIONAL PAPER.) 

ROCKY MOUNTAIN MINE TIMBERS. 1 

By Norman de W. Betts, 
Engineer in Forest Products, Forest Products Laboratory. 

STRENGTH. 

OBJECT OF THE TESTS. 

Approximately one-fourth of the timber cut in Colorado during 
1911 was consumed by the mining industries of that State. A num- 
ber of different species are used, and their relative strength is of con- 
siderable importance both to miners and producers of mine timbers. 
Native Douglas fir, the so-called "red spruce" of the Rocky Mountain 
region, has been the wood most suitable for use in mines, but it is 
no longer available for a very large part of the supply. The forests of 
lodgepole pine and Engelmann spruce, containing also several minor 
species, must furnish the bulk of the material. The Forest Service, 
in cooperation with the University of Colorado, has tested these dif- 
ferent timbers to determine their relative strength. 

Since the timbers are used both green and air-dried, the influence 
of moisture on their strength is of interest, and material was tested 
in order to bring out this relation. 

The relative value of fire-killed timber and of timber cut from 
growing trees has been the subject of much discussion. Since con- 
siderable dead timber is used in the mines, and a large supply is avail- 
able, tests on this kind of material were included, with the idea of 
determining its strength in the round form for comparison with 
material cut green. 

MATERIAL. 

The material tested 2 consisted of round beams and of props and caps 
representative of the market run of timber used in the coal mines. 
The props were from 5 to 6 inches in diameter and 6 feet long; the 
caps from 5 to 6 inches in diameter and 8 feet long; the beams nomi- 
nally 8, 10, and 12 inches in diameter and 16 feet long. Table 1 
gives a list of the material tested, and shows the form and number of 

i This paper is of interest to miners and producers of mine timbers and will be suitable for distribution in 
Idaho, Montana, Wyoming, Colorado, Nevada, Arizona, and New Mexico. 

2 The material for the tests described in this report was in part donated by the Northern Coal & Coke Co. 
of Denver and in part obtained from several national forests located in Colorado. The tests were made at 
the timber-testing station of the Forest Service, which is conducted in cooperation with the University of 
Colorado, at Boulder. 

29206°— 14- 1 



BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 



the specimens, the kind of wood, the locality where secured, and the 
number of the table in which the individual tests are recorded. 



Table 1. — Material tested. 



Species and form of 


Individual test 
records given in — 


Number 
of pieces. 


Source. 


material. 


Table 
No. 


Reference 
Nos. 


Lodgepole pine (ship- 
ment A): 

Round props 


/ 11 
\ 12 

/ I 3 

I 14 

/ 11 
1 12 
/ 13 
I 14 

/ 15 
I 16 

/ I 5 
I 16 

/ 11 
I 12 
/ 13 
I 14 

/ 11 
I 12 
/ 13 
I 14 

/ 11 
I 12 
/ 13 
I 14 

/ 11 
I 12 
/ 13 
\ 14 

/ 11 
\ 12 
/ 13 

\ I 4 

/ 11 
I 12 

/ 13 

I 14 


ItolO 
lto5 

ItolO 
lto5 

11 to 20.... 
6 to 10 
11 to 20.... 
6 to 10 

lto30 

1 to 15 ... . 

1 tola 
1 to 30 

lto9 
lto3 
1 to 9 
lto5 

1 to 11 
lto7 
ltoll 
lto5 

ItolO 

I to 5 
ItolO 
lto5 

ItolO 

lto5 

ItolO 
lt0 5 

ItolO 
lto5 
ItolO 
lto5 

II to 20.... 
6 to 10 

11 to 20.... 
6 to 10 


i 15 
} 15 

I 15 
I 15 

I 45 

} 45 

I 12 
I U 

} 18 
1 16 

I 15 
I 15 

1 15 
I 15 

I 15 

} 15 

> » 

} » 


[Yards of Northern Coal & Coke Co., at Louisville, 
i Colo . Probably cut on the west slope of the divide 
[ in Colorado. 

Do. 


Lodgepole pine (ship- 
ment B): 

Round props 


(Yards of Northern Coal & Coke Co. Probably cut 
\ on east slope of the divide in Boulder Co., Colo. 

Do. 


Lodgepole pine: 


/Gunnison National Forest, Colo. (Cut from live 
\ timber.) 

/Gunnison National Forest, Colo. (Cut from tim- 
\ ber standing dead for 30 years.) 

(Partly from yards of Northern Coal & Coke Co., 
\ partly from Arapahoe National Forest, Colo. 
Do. 


Lodgepole pine (fire 
killed): 


Alpine fir: 

Round props 


Engelmann spruce: 
Round props 


/Partly from yards of Northern Coal & Coke Co., 
\ partly from Pike National Forest, Colo. 

Do. 


Douglas fir: 

Round props 


/Partly from yards of Northern Coal & Coke Co., 
\ partly from Gunnison National Forest. 

Do. 


Bristle-cone pine: 

Round props 


Pike National Forest, Colo. 
Do. 


Western yellow pine 
(shipment A): 

Round props 

Caps 


/Pike National Forest, Colo. (Shipped as "Black 
\ Jack.") 

Do. 


Western yellow pine 
(shipment B): 

Round props 


/Partly from yards of Northern Coal & Coke Co., 
\ partly from Gunnison National Forest. 

Do. 







The material from the National Forests was received at the labora- 
tory in a green condition. The timbers from the yards of the coal 
company were partially air-dried. Upon arrival at the testing sta- 
tion all green material was barked and some of the specimens were 
soaked in water, while others were piled to air-season. The object 
of the water-soaking was to keep the timber in a green condition 
until tested or, in the case of the dead beams, to increase the moisture 
content to a point which would enable them to be compared with 
green material. The material cut green and water-soaked is used as 
the basis for making the comparisons with air-dry material. 



ROCKY MOUNTAIN MINE TIMBERS. 3 

The water-soaked material was placed in a small pond during the 
summer months and the first tests were made after 60 days and the 
last after 125 days of soaking. No means were available to give 
complete submersion. The caps and props were tied in bundles of 
five and the beams were rafted, iron rails being used to help submerge 
a part of the material. At intervals of two or three days the bun- 
dles and the individual beams were turned to make the soaking as 
uniform as possible. 



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oouaut FIN 



EMELMANU SPRUCE 



WIITIRN YltWW PINE 
SHIPMENT * 



BRISTLE -CONE PINE 



"1000 2000 3000 4000 

CRUSHINS STREHQTH AT MAXIMUM LOAD - POUNDS PER SQUARE INCH 

Fig. 1.— Comparison of different species; 6-inch round mine props— air-dried and green. 
RESULTS OF TESTS. 

Summaries of the results of the tests showing the average, maxi- 
mum, and minimum of each group are presented in Tables 2 (props) , 
3 (caps), and 4 (beams). Results of the individual tests on the 
green props are recorded in Table 11, on the air-seasoned props in 
Table 12, on the caps in Tables 13 and 14, and on the beams in 
Tables 15 and 16. 

PROPS AND CAPS. 

The relative strength of air-seasoned and green material for each 
species and the relative strength of the different species are shown 



4 



BULLETIN 77, U. S. DEPARTMENT OF AGRICULTUKE. 



graphically in figures 1 and 2. The increase in strength of the props 
due to seasoning is very evident in each species, and the average 
strength of the seasoned props of all species is 2.3 times that of the 
green ones at both maximum load and elastic limit. In the case of 
the caps the average strength of the dry timbers at the maximum 
load is 1.6 and at elastic limit 2.2 times the strength of the green 
timbers. While at the elastic limit the influence of the moisture 



SSAIR WYi 



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S'GREEN 



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QREEN ■ ' :...,..:.. .46971 



^69543 



O0U0LAS FIR 



L0DOEP0LE PINE 
SHIPMENT -A- 



BRISTLE-CONE PINE 



ENGELMANN SPRUCE 



WESTERN YELLOW PINE 
SHIPMENT -A- 



ALPINE FIR 



L0D0EP0LE PINE 
SHIPMENT -B- 



WESTERN YELLOW PINE 
SHIPMENT -B- 



MOO 2000 3000 4000 5000 6000 7000 8000 9000 

MODULUS OF RUPTURE - POUNDS PER SQUARE INCH 

Fig. 2.— Comparison of different species; 6-inch round mine caps— air-dried and green. 

was practically the same for both the crushing and bending tests, at 
the maximum load it is much more pronounced in the crushing tests. 
Stiffness in bending was increased by seasoning to 1.4 times the 
green value. There appears to be no marked variation in this 
strength ratio among the various species tested. It is slightly below 
the average in Douglas fir, due to the consistently high values for 
the green material in comparison with the other species, 



ROCKY MOUNTAIN MINE TIMBERS. 5 

Table 2. — Summary of crushing tests on round mine props (nominal size, 5-inch top by 

6 feet long). 

GREEN (WATER SOAKED). 



Species, number of tests. 







Diameter. 




Rings 
per 






Moisture. 








inch. 


Top. 


Butt. 


Per cent. 
75.7 
102.0 
48.3 


40 
56 
28 


Inches. 
5.73 
6.13 
4.93 


Inches. 
6.18 
6.92 
5.33 


70.8 
108.2 
57.5 


43 

58 
31 


5.90 
7.00 
4.85 


6.58 
7.56 
6.05 


91.0 
123.6 
38.6 


26 
42 
13 


4.90 
5.37 
4.62 


5.65 
6.05 
5.38 


62.3 

89.1 
38.1 


32 
46 
19 


4.95 

6.20 
4.14 


5.80 

7.08 
5.09 


50.5 
91.6 
30.0 


39 
76 
17 


5.48 

6.84 
4.93 


6.05 
7.16 
5.41 


85.9 
109.0 
56.1 


35 
43 
31 


4.58 
5.33 
3.98 


5.38 
6.40 
4.77 


96.1 
116.1 
83.2 


14 
16 
13 


4.44 

4.78 
4.14 


5.20 

5.60 
4.94 


82.0 
113.2 
54.8 


18 
32 

11 


5.35 
5.65 
5.01 


6.00 
6.17 
5.73 



Crushing 
strength 
at maxi- 
mum 
load. 



Crushing 

strength 

at elastic 

limit. 



Modulus 
of elas- 
ticity. 



Lodgepolepine fshipment A); lOtests: 

Average 

Maximum. . ., 

Minimum 

Lodgepole pine (shipment B ); 10 tests: 



Maximum 

Minimum 

Alpine fir; 9 tests: 



Maximum 

Minimum 

Engelmann spruce; 11 tests: 

Average 

Maximum 

Minimum 

Douglas fir; 10 tests: 

Average 

Maximum 

Minimum 

Bristle-cone pine; 10 tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment A); 10 
tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment B); 
10 tests: 

Average 

Maximum 

Minimum 



Lbs. per 

sg. in. 

1,865 

2,285 

1,440 

1,605 
1,890 
1,169 

1.920 
2,355 
1,573 

1,750 
2,115 
1,511 

2,580 
2,870 
2,200 

1,657 

2,026 
1,364 



1,475 
1,681 
1,269 



1,940 
2,410 
1,668 



Lbs. per 

sq. in. 

1,495 

1,981 

1,049 

1,240 
1,559 



1.490 
1,944 
1,268 

1,347 

1,755 
1,062 

2,130 
2,438 
1,885 

1,310 

1,590 
965 



1,201 
1,412 
1,038 



1,450 
1,883 
1,132 



1,000 lbs. 

per sq. in. 
599 
839 
343 

496 
621 
387 

541 
706 
401 

529 

686 
358 

758 
865 
596 

508 
638 
390 



443 
516 
345 



561 
762 

448 



AIR SEASONED. 



Lodgepole pine (shipment A); 5 tests 

Average 

Maximum 

Minimum 

Lodgepolepine (shipmen' B); 5 tests 

Average 

Maximum 

M inimu m 

Alpine fir; 3 tests: 

Average 

Maximum 

Minimum 

Engelmann spruce; 7 tests: 

Average 

Maximum 

Minimum 

Douglas fir; 5 tests: 

Average 

Maximum 

Minimum 

Bristle-cone pine; 5 tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment A) 
5 tests: 

Average 

Maximum 

' Minimum 

Western yellow pine (shipment B) 
5 tests: 

Average 

Maximum 

Minimum 



11.5 
12.3 
11.0 


46 
57 
34 


4.93 
5.17 
4.77 


5.43 

5.57 
5.17 


4,130 
4,770 
3,340 


3,513 
4,190 
2,750 


12.2 
15.9 
11.0 


45 
50 
42 


4.81 
5.25 
4.01 


5.44 
5.73 
5.01 


5,568 
6,340 
4,980 


4,438 
4,980 
4,010 


11.6 
12.4 
10.5 


18 
23 

15 


4.27 

4.46 
4.06 


5.28 
5.41 
5.09 


4,097 
4,260 
3,910 


3,530 
3,875 
3,165 


11.8 
13.7 
10.9 


33 
50 
16 


4.42 

5.09 
3.50 


5.29 
5.97 
4.62 


4,122 
5,560 
2,990 


3,297 
4,290 
2,410 


12.3 

13.7 
11.5 


49 
76 
28 


4.85 
5.33 
4.30 


5.33 

6.05 
4.62 


4,634 
5,720 
2,960 


3,617 
4,450 
2,340 


12.4 
12.6 
12.2 


38 
45 
30 


3.68 
3.98 
3.18 


4.44 

4.85 
4.22 


3,501 
4,390 
2,340 


2,823 
3,512 
2,013 


11.7 
13.4 
10.5 


14 
16 
11 


3.93 
4.30 
3.50 


4.78 
4.85 
4.62 


3,764 
5,330 
3,050 


3,401 
4,780 
2,470 


11.7 
13.0 
10.9 


18 
31 
12 


4.82 
4.93 
4.62 


5.44 
5.65 
5.25 


4,132 
4,790 
3,120 


3,266 
3,770 
2,270 



993 

1,194 

875 

1,282 
1,452 
1,135 

978 

1,043 
890 

1,042 

1,321 

703 

1,131 

1,324 

873 

826 

1,023 



887 

1,146 

626 



956 

1,160 

628 



6 BULLETIN 77, U. S. DEPAETMENT OF AGRICULTURE. 

Table 3. — Summary of bending tests on round mine caps (nominal size, 5-inch top by 
8 feet long; span, 7 feet; third-point loading). 

GREEN (WATER SOAKED). 



Species, number of tests. 



Moisture. 


Rings 
per 


Diameter. 








inch. 


Top. 


Butt. 


Per cent. 
89.3 
133.3 
56.7 


43 
61 
23 


Inches. 
5.59 
5.90 
5.17 


Inches. 
6.20 
6.68 
5.60 


60.6 
89.5 
40.1 


43 
52 
31 


5.78 
6.00 
5.25 


6.45 

6.75 
6.00 


99.5 
147.2 
57.6 


21 
36 

8 


4.65 
5.63 
4.13 


5.72 
6.50 
5.38 


54.3 
74.6 
36.3 


30 
45 

17 


5.16 
6.00 
4.44 


6.40 

7.00 
5.88 


69.4 
119.1 
32.6 


27 
38 
16 


4.78 
6.25 
4.00 


5.66 
7.00 
5.00 


74.3 
96.1 
66.2 


37 
62 
25 


4.63 
5.63 
3.38 


5.62 
7.00 
4.00 


88.5 

106.3 

71.1 


13 
15 
12 


4.39 
4.80 
3.75 


5.60 
6.25 
4.75 


147.1 
198.4 
86.5 


26 
42 
15 


4.42 
5.00 
3.62 


5.45 
6.12 
5.00 



Modulus 

of 
rupture. 



Fiber 

stress at 

elastic 

limit. 



Stiffness 
factor 

0&) 



Lodgepole pine (shipment A); 10 
tests: 

Average 

Maximum 

Minimum. 

Lodgepole pine (shipment B); 10 
tests: 

Average 

Maximum 

MiriiTTirrm 

Alpine fir; 9 tests: 

Average 

Maximum 

Minimum 

Engelmann spruce; 11 tests: 

Average 

Maximum 

Minim nm 

Douglas fir; 10 tests: 

Average 

Maximum 

Minimum 

Bristle-cone pine; 10 tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment A); 10 
tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment B); 10 
tests: 

Average 

Maximum 

Minim urn 



Lbs. per 

sq. in. 

5,172 

6,460 

4,040 



4,768 
6,180 
3,585 

4,139 
5,260 
1,945 

5,308 
J, 280 
3,500 

6,568 
7,310 
4,840 

4,578 
5,480 
3,500 



4,333 
4,960 
3,860 



4,897 
6,190 
3,320 



Lbs. per 

sq. in. 

3,104 

3,830 

2,635 



2,762 
3,555 
2,090 

2,450 
2,910 
1,782 

2,709 
3,665 
1,991 

3,455 
4,675 
2,505 

2,' 459 
3,960 
1,666 



2,170 
2,775 
1,553 



2,890 
3,540 
2,148 



AIR SEASONED. 



Lodgepole pine (shipment A); 5 tests: 

Average 

Maximum 

Minimum 

Lodgepole pine (shipment B) ; 5 tests: 

Average 

Maximum 

Minim tun 

Alpine fir; 5 tests: 

Average 

Maximum 

Minimum 

Engelmann spruce; 5 tests: 

Average 

Maximum 

Minimum 

Douglas fir; 5 tests: 

Average 

Maximum 

Minim um 

Bristle-cone pine; 5 tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment A); 5 
tests: 

Average 

Maximum 

Minimum 

Western yellow pine (shipment B); 5 
tests: 

Average 

Maximum 

Minimum 



11.4 
11.9 
10.6 


54 
72 
33 


4.76 
5.09 
4.54 


5.21 
5.49 
5.09 


9,026 
11,630 
7,180 


6,600 
8,640 
4,790 


11.1 
11.7 
10.6 


44 
47 
42 


4.84 
5.41 
4.54 


5.49 
5.73 
5.33 


6,954 
9,620 
4,490 


5,962 
7,290 
4,230 


11.4 
12.1 
10.4 


26 
37 
20 


4.22 
4.62 
3.66 


5.28 
5.57 
5.09 


7,340 
9,350 
5,270 


5,460 
6,600 
4,320 


10.9 
11.8 
8.8 


37 
45 

27 


4.41 
5.33 
3.50 


5.35 

6.05 
4.62 


8,242 
9,900 
6,260 


6,618 
7,340 
5,190 


11.8 
12.3 
11.4 


23 
29 

15 


4.30 
4.77 
3.82 


5.20 

5.57 
4.77 


9,232 
10,960 
5,790 


6,842 
7,660 
5,100 


11.5 
12.5 
10.7 


37 
52 

27 


3.82 

4.22 
3.50 


4.98 
5.25 
4.54 


8,408 
9,550 
7,000 


5,684 
6,700 
4,120 


10.3 
10.6 
9.4 


14 
15 
13 


3.58 
3.66 
3.50 


4.85 
5.09 
4.62 


7,660 
9,770 
5,660 


5,770 
7,730 
3,870 


10.7 
11.4 
10.3 


21 
26 
17 


3.90 
4.22 
3.58 


5.12 
5.41 
4.62 


6,012 
7,360 
4,210 


4,938 
5,830 
4,220 



EOCKY MOUNTAIN MINE TIMBERS. 7 

Table 4. — Summary of bending tests on round beams, 16 feet long (span, 15 feet; third- 
point loading). 

GREEN (WATER SOAKED). 



Species, size, number of 


Moisture. 


Rings 
per 
inch. 


Diameter. 


Modulus 

of 
rupture. 


Fiber 

stress at 

elastic 

limit. 


Stiffness 
factor 

(1) 


Work 
to maxi- 


tests. 


Top. 


Butt. 


mum 
load. 


Lodgepole pine, cut from 
live timber: 
8-incb butt, 10 tests— 


Per cent. 
77.3 
99.4 
62.1 

90.2 
118.2 
73.4 

91.8 
99.6 
78.3 

38.1 
45.2 
35.0 

40.1 
47.7 
29.8 

37.2 
41.7 
27.8 


32 
37 

28 

27 
32 
21 

23 
24 
18 

44 
52 
34 

40 
48 
35 

28 
34 
24 


Inches. 
6.77 
7.32 
6.29 

8.26 
9.23 
7.24 

9.82 
10.82 
9.23 

7.00 
7.08 
6.92 

8.21 
9.23 
7.56 

10.00 
10.98 
9.31 


Inches. 
8.20 
8.75 

7.76 

9.97 
10.74 
9.39 

11.62 
12. 41 
10.98 

8.50 
9.06 
7.80 

10.24 
11.14 
9.71 

12.47 
12.97 
11.77 


Lbs. per 

sq. in. 

5,348 

6,210 

4,860 

5,233 
6,230 
4,510 

5,095 
6,2 7 
4,230 

5,448 
6,580 
3,570 

4,940 
6,500 
3,870 

4,430 
5,680 
3,820 


Lbs. per 

sq. in. 

3,120 

4,200 

2,425 

3,008 
3,905 
2,038 

2,987 
3,780 
2,298 

2,905 
3,690 
2,210 

2,950 
4,180 
1,592 

2,320 
2,960 

1,828 


10.99 
13.42 
9.26 

10.32 
11.73 

7.48 

10.23 
13.70 
8.16 

10.38 
13.25 
8.00 

8.84 
10.97 
7.09 

7.71 
9.71 
5.18 


Inch lbs. 

per cu. in. 

4.7 




6.6 




2.6 


10-inch butt, 10 tests— 


5.5 




7.8 




3.2 


12-inch butt, 10 tests- 


5.2 




7.0 


Minimum 


2.0 


Lodgepole pine, cut from 
timber after standing 
dead for 30 years: 
8-inch butt, 5 tests- 
Average 


5.3 




7.6 


Minimum 


2.3 


10-inch butt, 5 tests — 


3.4 




5.4 




1.6 


12-inch butt, 5 tests — 


4.3 




8.2 




2.0 







AIR SEASONED. 



Lodgepole pine, cut from 
live timber: 

8-inch butt, 5 tests — 

Average 

Maximum 

Minimum 

10-inch butt, 5 tests- 
Average 

Maximum 

Minimum 

12-inch butt, 5 tests — 

Average 

Maximum 

Minimum 

Lodgepole pine, cut from 
timber after standing 
dead for 30 years: 

8-inch butt, 9 tests- 
Average 

Maximum 

Minimum 

10-inch butt, 10 tests- 
Average 

Maximum 

Minimum 

12-inch butt, 11 tests- 
Average 

Maximum 

Minimum 



16.8 
19.9 
15-2 


32 
34 
29 


6.99 
7.64 
6.37 


8.04 
8.36 
7.64 


7,748 
9,310 
7,160 


5,018 
5,290 
4,640 


14.05 
16.80 
12.43 


17.1 
18.3 
14.6 


25 
27 
23 


8.09 
8.59 
7.08 


9.77 
10.03 
9.55 


6,948 
9,060 
4,480 


4,816 
5,940 
3,190 


13.33 
18.75 
10.31 


19.3 
21.8 
17.7 


22 
23 
21 


9.73 
9.95 
9.55 


11.51 
11.81 
11.14 


5,409 
6,350 
3,745 


3,741 
4,340 
2,875 


9.57 
11.62 
6.85 


13.7 
14.6 
11.5 


40 
51 
34 


6.98 
7.64 
6.45 


8.39 

8.91 

• 7.48 


5,625 

7,780 
3,843 


4,649 
6,720 
3,195 


10.92 
12.51 
9.58 


12.9 

14.4 
12.1 


34 
42 
24 


8.27 
8.91 
7.64 


10.11 
10.66 
9.31 


5,166 
8,970 
2,690 


4,489 
6,400 
2,585 


10.54 
13.53 
8.06 


13.8 
16.6 
12.0 


31 

37 
24 


9.16 
11.14 
9.07 


12.15 
12.49 
11.46 


4,720 
7,310 
2,060 


3,925 
5,960 
1,343 


9.84 
12.29 
8.12 



3.8 
4.9 
2.7 

3.1 
4.0 
1.5 

2.3 
3.0 
1.2 



2.1 
5.6 



2.3 

4.2 

.5 

1.7 

3.8 

.4 



The average results do not show a consistent difference in the 
relative strength of the various species tested. Figures 1 and 2 show 
that, with the exception of the green props and caps of Douglas fir 
and the dry props of lodgepole pine (Shipment B), there is not a 
very large difference in the strength of the various shipments. Ty 



8 BULLETIN" 77, U. S. DEPARTMENT OP AGRICULTURE. 

is apparent from the various positions occupied by the different 
shipments of lodgepole pine and western yellow pine that species is 
not in itself a reliable guide to strength in the selection of material 
of this form and size. With clear material, consistent differences 
would probably be found between some of the species, but in the 
props especially the degree of straightness of the piece and the pres- 
ence of knots seem of greater effect than the species. 



The results of the tests on the three sizes of 16-foot round beams 
of lodgepole pine are shown graphically in figures 3 and 4. With 
the exception of the work to maximum load, all the strength functions 
decrease in value with increase in the diameter of the beam. The 
amount of this variation differs in the different kinds of material, 
being least in the green, greatest in the air-dried, and intermediate 
in the dead timber. The reason for the decrease in the unit strength 
of the larger beams is not apparent. It is not due to visible defects, 
such as cause a decrease in the unit stress in large stringers when 
compared with small clear pieces cut from them, since the defects in 
the 8 and 12 inch beams did not differ in kind or in appearance. 
The fact that stiffness decreases in the same manner as strength 
corroborates this statement, since such defects as knots and checks 
do not generally affect stiffness up to the elastic limit. The differ- 
ence may, however, be due, at least in part, to rate of growth, which 
increases in all cases with increase in diameter. The smaller beams 
were apparently cut from the suppressed growth of a fairly even- 
aged stand. The unit weight of the beams does not vary consist- 
ently with the strength. The dry weight per cubic foot of the air- 
dried beams is lowest in the 12-inch size, but for the dead beams 
the weight is highest in this size. 

The relative values of the dead, green, and air-dried timbers are 
also indicated in figures 3 and 4. In strength the dead material 
falls between that of the air-dried and green, being close to the air- 
dried at the elastic limit and close to the green at the maximum load. 
The air-dried material is the stiffest, the green and dead having 
practically equal values for this factor. The closeness of the values 
for green and dead water-soaked material and a comparison of their 
curves with those of the dry timbers show very clearly the effect of 
moisture in reducing the stiffness and strength at the elastic limit. 
In work to maximum load, which is an indication of toughness, the 
order of the curves is reversed, the green and water-soaked beams 
having values about twice as great as the dry material. The posi- 
tion of the dead water-soaked beams, especially, brings out the fact 
^at the greater brittleness of the dead or air-dried material is due to 
iss and not to a deterioration of the wood. Drying the beams 



ROCKY MOUNTAIN MINE TIMBERS. 

























































9000 
















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DIAMETER OF BUTT- INCHES 

Fig. 3. — Relation of unit strength of 16-foot round beams to diameter and condition. 
29206°— 14 2 



10 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 

increased the strength and stiffness of the wood but decreased its 
toughness. 




INCH-POUNDS PER CUBIC INCH 



Fig. 4.— Relation of unit strength of 10-foot round beams to condition; based on average values of the 

three sizes tested. 

In comparing fire-killed and green material, the grade of both, in 
regard to ordinary defects, should be taken into consideration. The 



EOCKY MOUNTAIN MINE TIMBEES. 11 

dead material tested was cut from an area supposedly burned over 
in 1880. In general, the surface was covered with a network of 
shallow worm marks (made when the bark was on and probably of 
no influence on the soundness). The beams, even the larger ones, 
were very rough and knotty, and were of poorer grade in respect to 
condition of knots than those cut green. The cross sections in gen- 
eral were sound, though here and there along the length were places 
beginning to form punky pockets at the surface. The fact that this 
material under test gave values up to the elastic limit nearly equal 
to those of the air-dried beams is of considerable interest, as it indi- 
cates that it is in excellent condition for the uses to which round 
material is ordinarily put. 

CONCLUSIONS. 

The tests indicate that : 

1. An air-dried mine prop is superior to a green one as follows: 

Strength at elastic limit 2.3 times as great. 
Strength at maximum load 2.3 times as great. 
Stiffness 1.9 times as great. 
An air-dried mine cap is superior to a green one as follows: 
Strength at elastic limit 2.2 times as great. 
Strength at maximum load 1.6 times as great. 
Stiffness 1.4 times as great. 

2. With the exception of Douglas fir, there seems to be as much variation in the 

strength of one species procured in different places as among the different 
species themselves. This is probably the result of defects such as checks, 
knots, and bends, which, in this size of material (5 to 6 inch diameter round 
caps and props), apparently overbalance the differences in the actual strength 
of the clear wood. 

3. The unit strength and stiffness of 16-foot round beams decrease with an increase 

in size. The smaller beams tested, however, represented a slower growth 
material and were probably suppressed trees. 

4. Beams cut from timber standing dead for about 30 years showed a strength in- 

termediate between green and air-dried material cut from live timber. The 
tests tend to corroborate the opinion that timber cut from dead trees can be 
graded on the same basis as other material; that is, the quality of the wood has 
not changed, from the fact that it has seasoned on the stump, and deterioration, 
if present, will be indicated by signs of decay. Checking in material to be 
used in the round form can hardly be considered as a defect, as it occurs in all 
air-dried round material. 

CONSUMPTION AND DURABILITY. 
CONSUMPTION OF MINE TIMBERS IN COLORADO. 

The statistics here presented were collected to show the consump- 
tion of timber by the mining industry of Colorado x in 1911. They 
were obtained by sending a card to the mine operators of the State, 
requesting them to furnish the amounts, costs, and species of tim- 

i Colorado was chosen partly because of its importance as a mining State; partly because for the year 
1911 an estimate of the entire production of wood products, including lumber, poles, crossties, round mine 
timbers, and fuel was also available for direct comparison, and partly because the State is near the center 
of distribution of the species of mine timbers tested. 



12 



BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 



ber used in the mines, and information concerning the life of the 
timber and the extent to which methods to prevent decay had been 
employed. A small part of the material included may have been used 
in structures above ground. 

Reports were requested from 823 operators, 110 of whom were 
coal-mine and 713 metal-mine operators. Out of 352 replies, 179 
(15 coal-mine and 164 metal-mine operators) reported that no timber 
was used during 1911, while 173 operators reported the use of timber 
on which the following statistics are based. 

In addition to the material reported by the tables, about 1,745 
cords (or 872,500 b. m.) were used for fuel. 

Nearly all the timber used came from within the State. About 
800,000 board feet was reported as coming from outside, mostly 
Douglas fir from Oregon, with a small amount of pine from New 
Mexico. 

The timbers for use in the coal mines ranged in size from about 5 
to 7 inches in diameter and from 7 to 18 feet in length. In the 
metal mines 8 to 10 inch diameters were the principal sizes, though 
timbers varying from 6 to 20 inches were reported. Lagging was 
usually 3 to 4 inches at the small end, and mine ties were 4 by 4 or 
4 by 5 inches in section and from 36 inches in length in the metal 
mines to 54 inches in the coal mines. 



Table 5. — Amounts and values of mine timbers used in Colorado in 1905, based on 

reports of mine operators. 





Num- 
ber of 
mines. 


Total amounts. 


Total values. 


Cost per M b. m. 


Mines reporting. 


Round, 
M b. m. 


Sawed, 
M b. m. 


Round. 


Sawed. 


Round. 


Sawed. 




69. 

418 


7,893 
18, 152 


457 
13, 061 


$153, 152 
284, 861 


$15, 428 
251,798 


$19.40 
15.69 


$33. 76 




19.28 






Total (all mines) 


487 


26,045 


13.518 


438, 013 


267. 226 


16.82 


19.77 












39,5fi3Mb.m. 


$705-239 



















Table 6. — Amounts and values of mine timbers used in Colorado in 1911, based on 

reports of mine operators. 





Num- 
ber of 
mines. 


Total amounts. 


Total values. 


Cost per M b. m. 


Mines reporting. 


Round, 
M b. m. 


Sawed, 
M b. m. 


Round. 


Sawed. 


Round. 


Sawed. 




77 
187 


10,859 
6,601 


1,000 
6,406 


$307, 372 
139,030 


$20,368 
141.185 


$28. 20 
21.10 


$20.37 




22.00 








Total (all mines) 


264 


17,460 


7,406 


446,402 I 161,553 


25.50 


21.80 




24,$66 


$607,955 



















The amounts were reported in linear feet, in board feet (log scale), 
in cubic feet, and in cords. To reduce these various units to the 



ROCKY MOUNTAIN MINE TIMBERS. 



13 



same basis 6 board feet were considered equivalent to 1 cubic foot 
of round timber and 500 board feet to a cord. 

Table 5 is compiled from Forest Service Circular 49 for purposes 
of comparison. Table 6 gives similar data obtained for 191 l. The 
two tables are not directly comparable, however, since the propor- 
tion of timber used by the mines reporting, to the whole consumption 
in the State, is not definitely known in either case. 

PRODUCTION OF MINE TIMBERS IN COLORADO. 

A study of timber products was made in Colorado for the year 
1911, and this furnishes some basis for an estimate of the probable 
total consumption of timber by the mines, including both round and 
sawed forms. The total production, including lumber, crossties, 
mine timbers, poles, fuel, and farm timbers, on the basis of the re- 
ports of the national forest supervisors, for both Government and 
private lands, was 222,808,000 board feet. The total production of 
round mine timbers was 36,274,000 board feet. The consumption 
reported, as shown in Table 6, was 17,460,000 feet of round material 
and 7,406,000 feet of sawed lumber. If the figure for production 
may be assumed as approximately correct for the actual total con- 
sumption and the proportion between the amounts of sawed and 
round forms reported holds for the total consumption, the total 
sawed timber used in the mines would be 15,370,000 feet and the 
total timber, round and sawed, would be 51,644,000 feet. This rep- 
resents close to $1,250,000 in total value and 23 per cent of all the 
timber produced in the State. 

PRODUCTION BY SPECD3S. 

The relative amounts of the different species used could not be 
obtained from the reports submitted by the mine operators. Based 
upon production, however, a close estimate is given in Table 7. The 
local names for certain species are different from those adopted 
by the Forest Service, and in order to make clear what woods are 
referred to, the scientific name, the common name used by the Forest 
Service, and the name used locally in Colorado are given below: 



Scientific name. 

Pinus contorta. 
Pinus ponderosa 

Pinus flexilis. 
Pinus aristata. 
Pseudotsuga taxifolia. 
Picea engelmanni. 
Picea parryana. 
Abies lasiocarpa. 
Abies concolor. 
Populus treniuloides. 



Common name used by 
Forest Service. 

Lodgepole pine. 
Western yellow pine. 

Limber pine. 
Bristle-cone pine. 
Douglas fir. 
Engelmann spruce. 
Blue spruce. 
Alpine fir. 
White fir. 
Aspen. 



Common name used locally. 



White pine. 
Black jack 
pine. 

Fox-tail pine. 
Red spruce. 
White spruce. 
Water spruce. 
Balsam. 
Black balsam. 
Quaking-asp. 



and yellow 



14 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 

Table 7. — Amounts by species of round mine limbers produced in Colorado in 1911. 



Species. 



Lodgepole pine 

Engelmann spruce. . . 

Douglas fir 

Western yellow pine. 

Limber pine 

Bristle-cone pine 

Aspen 

Alpine fir 

Blue spruce 

White fir 

Oak 



Amount. 



Total 36, 274, 000 



Boardfeet. 

23,421,000 

8, 242, 000 

2,244,000 

1,354,000 

431,000 

183,000 

149,000 

109,000 

75,000 

65,000 

1.000 



Percent- 
age of 
total. 



100 



Table 8. — Unit costs for various diameters. 



Diame- 
ter. 


Cost per piece 16 
feet long. 


Cost per linear foot. 


Cost per inch of 
diameter 16 feet 
long. 


Inches. 
3 
4 
6 
8 
10 
12 
14 
16 


$0.35 

. 40 to $0. 50 
. 45 to .65 
.60 to 1.25 
1.15 to 1.60 
1.50 to 2.15 
2. 00 to 2.25 
2.50 


$0. 022 
. 025 to $0. 031 
.028 to .041 
. 038 to . 078 
. 072 to . 100 
. 094 to . 135 
.125 to .141 
.156 


$0. 117 
. 100 to $0. 125 
.075 to .108 
. 075 to . 156 
.115 to .160 
. 125 to . 180 
.143 to .161 
.156 



Table 7 shows that lodgepole pine is the main source of supply for 
round mine timbers, and, together with Engelmann spruce, makes up 
88 per cent of all the props cut. Douglas fir, although a very desir- 
able wood, formed only 6 per cent of the total. 



COSTS FOR DIFFERENT SIZES. 



Table 8, giving costs for props of various diameters, was compiled 
from such data submitted by the operators as were definite in regard 
to the size of the material. Several methods of purchasing round 
material were reported — cost per piece for a given length and diam- 
eter, cost per linear foot for a given diameter, and cost per inch of 
diameter at the small end for a given length. A large majority 
reported the cost per linear foot. 



LIFE OF TIMBERS. 



There was a large variation in the reported life of timbers in the 
different mines, especially in the metal mines. The timbers in the 
coal mines had an average life of only about one-half that found in 
the metal mines, but their size was also only about one-half as great. 
Tables 9 and 10 give the average values obtained from statements of 
the operators. 



ROCKY MOUNTAIN MINE TIMBERS. 



15 



Table 9. — Reported life of untreated round mine timbers in coal mines (mostly 5 to 7 

inches diameter). 



Conditions in mine. 



Average 

Poor ventilation. 
Good ventilation . 
Exceptional 



Doug- 
las fir. 



Years. 

5 

2 

10 

25 



Pine.i 



Years. 
4 
1 



Engel- 
mann 
spruce. 



Years. 
4 

1 



Alpine 
fir. 



Years. 
3 



Pifion. 



Years. 
4 
1 
6 



1 Includes lodgepole pine and western yellow pine. 

Table 10. — Reported life of untreated round mine timbers in metal mines (mostly 8 to 10 

inches diameter). 



Conditions in mine. 



Douglas 
fir. 



Western 
yellow pine 



Lodgepole 
pine. 



Engelmann 
spruce. 



Average 

Very poor ventilation . 
Constantly wet 



Years. 
9 
2 to 5 

20 to 40 



Years. 



lto 3 
15 to 25 



Years. 
7 
lto 2 



Years. 



lto 2 
15 to 20 



The conditions under which the estimates were made vary so much 
that the relative life of the different species is probably not reliable. 
For example, several operators reported that under the same condi- 
tions Douglas fir outlasts lodgepole pine or spruce two to three times; 
yet the average values show comparatively little variation among the 
species. 

The factors that cause variation in the life of the timbers are prin- 
cipally ventilation, moisture, acid mine water, and the condition 
of the timbers when placed. The influence of fresh and compara- 
tively dry air was clearly indicated in several mines which reported 
a life fully four times as long for the timbers in the intake shaft as 
for those in the return shaft (8 and 2 years, respectively). Several 
operators reported that they had increased the life of their timbers 
from two to three times by peeling and seasoning them before place- 
ment. Certain mines reported that their timbers were sound after 
standing from 25 to 35 years under conditions where they were nearly 
always wet, and in one or two cases the water was stated to contain 
"sulphuric acid" or "copper and arsenic," which probably acted as 
an antiseptic. Both constantly wet and constantly dry conditions 
appear, from the replies, to be favorable to a long life, while damp- 
ness, due to stagnant air, or alternating dryness and wetness, appears 
to furnish the best conditions for the growth of wood-destroying fungi. 



PRESERVATIVE TREATMENT. 



Preservative treatment to prevent decay was not regularly prac- 
ticed at any of the mines reporting. Sixteen operators referred to 
some use of preservatives, though none had had a long enough expe- 
rience to furnish data on the increased life from such treatment. The 
methods spoken of were dipping in creosote or crude oil, and brush 



16 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 

treatments with creosote, carbolineum, or crude oil. One operator 
referred to the disagreeable effect on the miners of the odor from the 
creosote in the mine. 

There was great variation in the replies to the question regarding 
the proportion of timber used for replacements made necessary by 
decay. Replies from 30 coal mines averaged 11 per cent (14 reporting 
per cent and none 100 per cent), and from 112 metal mines aver- 
aged 21 per cent (44 reporting per cent and 11 reporting 100 per 
cent). It is apparent that the economy of preservative treatment is 
a local problem with each mine. 

In order to decide whether it would be economical in any given case 
to apply treatment only a few factors concerning the present costs 
and life of the timbers are essential. The proper method 1 of treat- 
ment would depend upon species of wood, capacity of apparatus, and 
local conditions, but the preliminary steps could be taken on the basis 
of the following data : 

1. The amount and cost of material that goes annually toward 
replacing decayed timbers. 

2. The cost, in place, of the timbers used. 

3. The average life of the timber. 

The first of these factors will readily show whether the amount 
concerned is large enough to warrant further consideration of pre- 
servative treatment. In certain coal mines, where but few timbers 
are necessary in the permanent entries and where the majority of 
timbers are used in temporary positions, a brush treatment would 
probably be all that is warranted, unless impregnated material could 
be procured in the market. On the other hand, where a large amount 
of material is used to replace decayed timbers the installation of a 
small treating plant might be seriously considered. 

From the cost in place and the average fife of the timbers there can 
be calculated an annual charge, a measure of the relative economy, 
with which any other combination of cost and life (such as that 
resulting from a preservative treatment of the timber or perhaps 
from the use of some other kind of material) can be compared. In 
figure 5 is presented a series of curves, each for a definite initial cost 
of a timber or set of timbers, which show the relation between length 
of life and annual charge when compound interest on the investment 
is considered and maintenance is assumed for an indefinite time; 2 

> Forest Service Bulletin 10", The Preservation of Mine Timbers, by E. W. Peters, treats of various 
methods of preserving mine timbers from decay. 

2 The annual charges are figured on this basis so that a fair comparison can be made between different 
methods involving various combinations of costs and length of service. If a material were placed that would 
last forever its annual charge would be simply the interest on the cost in place. If the material must be 
replaced every so often, the annual charge represents the interest on a sum of money which, if placed at 
compound interest, would pay for the initial cost in place and all future replacements and would be itself 
used up at the end of the period of maintenance under consideration. If this period be of an indefinite 
length (forever), the annual charge is the interest on a sum of money sufficient to pay the present cost of 
installation and, by the accumulation of compound interest on the balance, take care of future replace- 
ments at the assumed intervals of time. 



ROCKY MOUNTAIN MINE TIMBERS. 



.17 



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AHHUAL CHARQE = R--^5|_-(M»5 
1.05-1 

RsllHrriAL COST IN PLACE-DOLLARS 
H=MFE OF TIMBER-YEARS 
JKTEREST 5 PERCENT 






































































































































































































































































































































































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LIFE 1H YEARS 

Fig. 5.— Relation between life of timbers and annual charge. 



29206°— 14— 3 



18 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 

The curves will show how much additional initial cost is warranted 
when a given increase in life due to the treatment under consideration 
is assumed and the initial cost and life for the existing conditions are 
known. The diagram also illustrates graphically, by the steepness 
of the curves, the great economy in prolonging the life of timbers 
that ordinarily last but a few years. 

To illustrate the use of the curves, assume that an operator wants 
to find out approximately what saving he would effect by carrying 
out some proposed scheme to lengthen the life of his timbers in cer- 
tain permanent openings. Assume that each timber set costs $6, 
including the expense of framing and setting. If its life is five years, 
its annual charge as shown by the curves is approximately $1.40. 
Let us next assume that the proposed treatment will double the life; 
that is, give the timbers a service of 10 years. A further inspection 
of the curves at the line of 10 years' life shows that the same annual 
charge of $1.40 results from an initial cost of $10.50. In other words, 
the economy of a timber that costs $6 in place and lasts five years is the 
same as one that costs $10.50 and lasts 10 years; and, therefore, the 
proposed treatment would pay if the final cost of the treated timber 
was anything less than $10.50. If we assume the cost of the treat- 
ment to be $1.50 for each timber (making the total cost in place $7.50) 
the annual charge would be about $1. The cost of using treated tim- 
bers would increase the total cost of timbering each year until the 
period of the natural (untreated) life of the timbers (five years in 
this example) had been passed; after that time, however, there would 
be a period of very low total costs until it was necessary to replace 
the treated material. The economy shown in an annual charge of $1 
in comparison with $1.40 represents the average conditions due to a 
continuous maintenance. It means, expressed in another way, that 
the investment required to maintain the untreated timber perma- 
nently would be $28, and that the investment for the maintenance 
of the treated timber would be $20, under the conditions given in 
this example. 



APPENDIX. 

METHODS, 

TESTING. 

The 6-foot props were tested in compression parallel to the grain 
at a speed of 0.119 inch per minute. A bearing block was used 
between the prop and the base of the machine. The compression of 
the prop, as indicated by the movement of the head of the testing 
machine, was read to thousandths of an inch by means of an Olsen 
deflectometer. Figure 6 shows a prop in the testing machine after 
failure. 

The 8-foot caps were tested on a 7-foot span with third-point load- 
ing. The tests were made on a 200,000-pound Riehle testing machine 
at a speed of 0.231 inch per minute. The ends were supported by 
curved cast-iron bearing blocks and the load applied at two points 
(one-third the length of the span from either end) through curved 
wooden blocks. Deflections were read at the center of the beam to 
hundredths of an inch by observing on a taut string the movement 
of a polished metal scale attached to the timber. The method of 
loading is shown in figure 7, all parts of the testing machine being 
omitted except the weighing platform. 

The 16-foot lodgepole pine beams were tested on a 15-foot span 
with third-point loading. The arrangement was similar to that 
used for the caps. 

MOISTURE DETERMINATIONS. 

A 1-inch section was cut from near the point of failure of each 
piece tested. This was immediately weighed and later dried to con- 
stant weight at the temperature of boiling water. The loss in weight 
divided by the dry weight, expressed in per cent, is the moisture 
content of the piece. 

GENERAL OBSERVATIONS. 

The length, weight, and diameters of the timbers were obtained 
j ust before testing. The rings per inch and the proportion of sap wood 
and of summerwood were obtained from a section cut near the point 
of failure. The values for the amount of summerwood are approxi- 
mate, as the summerwood bands were not distinctly marked in many 
of the pieces. 

COMPUTATIONS. 

The load and deflection at the elastic limit were obtained from the 
load-deflection curve, and at maximum load by direct observation. 

19 



20 



BULLETIN 77. U. S. DEPABTMENT OF AGBICULTUEE. 



The fiber stress at the elastic limit and the modulus of rupture 
were computed for the diameter and moment of inertia obtaining 
under the smaller loading point, the section being regarded as a 

true circle. The stiffness 




factor * 



was obtained 



from the moment of in- 
ertia (I) and the deflec- 
tion (d) at the center of 
the beam. These values 
for stiffness are compar- 
able for pieces of the 
same span only. The 
true modulus of elasticity, 
which is difficult to ob- 
tain accurately for a beam 
with a varying moment 
of inertia, depends upon 
the cube of the span. 
This relation is not con- 
sidered in the "stiffness 

P 
factor" used, j^ } and this 

causes the values for the 
7-foot span to be approxi- 
mately ten times as large 
as for the 15-foot span. 
The work to maximum 
load was calculated from 
the area under the load- 
deflection curve, and is 
given in terms of unit 
volume. In the calcula- 
tions involving the unit 
stresses of the props, the 
top area of the prop was 
used. 

The volume of the test 
pieces was calculated by 
multiplying the average 

Fig. 6.— Method used in testing mine props in compression. | ^ areas of the ton 

the butt, and the mean proportional between them, by the length. 
The weight per cubic foot was obtained from this estimated vol- 
ume, and is therefore given as "approximate." 



KOOKY MOUNTAIN MINE TIMBERS. 



21 



Table 11. — Data on individual crushing tests of green round mine props {nominal size, 

5-inch top by 6 feet long). 









eg 


& 


•e 




Diameter. 


A a 

"S3 
o a 


fi 


J 
3 




Species. 


CD 




3 t3 


.a 




•6 






s?a 


6003 

a J 

Is 


o t* 


Remarks. 




a 

>22 


i 

o 


OWU 

lis 


03 

60 

.a 


<D 


I 

S 1 


£ 


4^ - 

3 


1 -d 


or* 

O 






rt 


a 


<< 


« 


cq 


m 


Eh 


pq 


o 


o 


a 


























1,000 






















Lbs. 


Lbs. 


lbs. 








Per 


Lbs. per 
cu.ft. 




Per 


Per 






per 


per 


per 








c«nf. 




cent. 


cent. 


In. 


In. 


sq. in. 


sq. in. 


sq. in. 




Lodgepole 


l 


63.4 


26.23 


47 


26 


55 


5.17 


5.33 


1,885 


1,620 


587 


Grain slightly spiral. 


pine (ship- 


2 


85.6 


22.50 


47 


20 


73 


4.93 


5.57 


1,440 


1,049 


559 


Slightly crooked. 


ment A). 




























3 


64.0 


24.18 


40 


17 


41 


6.13 


6.37 


1,756 


1,355 


652 


Grain slightly spiral. 




4 


99.0 


22.23 


38 


16 


66 


5.65 


5.89 


1,808 


1,595 


343 






5 


48.3 


24.72 


28 


15 


28 


5.89 


6.13 


2,285 


1,981 


839 


5 knots, in failure 

plane. 
Unusually knotty. 




6 


65.3 


22.79 


43 


16 


50 


6.13 


6.92 


1,835 


1,356 


582 




7 


102.0 


21.48 


56 


20 


54 


5.57 


6.13 


1,820 


1,396 


546 


Grain spiral. 




8 


83.7 


23.46 


32 


13 


62 


•5.81 


6.45 


1,745 


1,509 


560 






9 


67.4 


24.22 


32 


14 


65 


5.99 


6.53 


1,800 


1,420 


602 


Do. 




10 


78.4 


25.70 


36 


18 


46 


6.05 


6.45 


2,281 


1,670 


719 


Do. 






75.7 


23.75 


40 


18 


54 


5.73 


6.18 


1,865 


1,495 


599 











Lodgepole 


11 


61.8 


24.57 


41 


18 


50 


5.81 


6.13 


1,712 


1,130 


539 


Slightly crooked. 


pine (ship- 


12 


63.3 


23.08 


46 


22 


65 


6.05 


6.84 


1,490 


1,250 


387 




ment B). 


13 


58.7 


26.40 


45 


20 


25 


6.13 


6.53 


1,890 


1,559 


442 


Do. 




14 


81.0 


22.76 


48 


20 


29 


5.65 


6.45 


1,782 


1,354 


468 






15 


57.5 


19.45 


58 


13 


31 


5.25 


6.05 


1,630 


1,292 


598 


Grain spiral. 




16 


82.4 


22.86 


38 


15 


58 


5.73 


6.21 


1,705 


1,396 


621 


Do. 




17 


108.2 


24.38 


35 


12 


73 


4.85 


6.21 


1,169 


866 


439 






18 


61.8 


22.21 


44 


16 


53 


5.73 


6.37 


1,655 


1,318 


481 






19 


69.6 


20.56 


31 


12 


50 


6.76 


7.42 


1,438 


891 


526 


Slightly decayed. 




20 


63.7 


22.39 


48 


14 


55 


7.00 


7.56 


1,590 


1,351 


463 


Grain spiral. 






70.8 


22. 86 


43 


16 


4S 


5.90 


6.58 


1,605 


1,240 


496 










Alpine fir. . . 


1 


58.5 


19.44 


23 


12 




5.17 


6.05 


1,770 


1,334 


463 






2 


38.6 


24.07 


42 


15 




5.37 


5.73 


2,355 


1,944 


706 






3 


119.9 


20.03 


32 


18 




4.70 


5.38 


1, 712 


1,441 


502 






4 


115.3 




28 


22 




4.90 


5.58 


1,573 


1,378 


401 


Grain slightly spiral. 




5 


86.3 


22.41 


25 


20 




5.00 


5.50 


1,930 


1,630 


547 


Do. 




6 


78.1 


20.28 


13 


14 




4.77 


5.65 


1,870 


1,568 


519 






7 


123.6 


21.58 


23 


16 




4.85 


5.41 


1,978 


1,300 


633 






8 


63.1 


22.82 


20 


10 




4.70 


5.65 


2,007 


1,268 


486 






9 


135.7 


20.22 


29 


9 




4.62 


5.57 


2,082 


1,551 


614 








91.0 


21.36 


26 


15 




4.90 


5.65 


1,920 


1,490 


541 










Engelmann 


1 


52.4 


23.32 


32 


13 




5.65 


7.08 


2,040 


1,755 


642 




spruce. 


2 


68.8 


24.14 


46 


18 




6.20 


7.00 


2,000 


1,459 


686 






3 


53.1 


24.08 


38 


14 




5.25 


5.73 


1,875 


1,293 


578 






4 


75.4 


22.98 


25 


16 




4.38 


5.41 


1,511 


1,062 


358 






5 


89.1 


22.82 


25 


20 




4.46 


5.16 


1,515 


1,280 


459 






6 


73.2 


24.20 


19 


14 




4.14 


5.09 


1,590 


1,340 


592 


Crooked. 




7 


72.2 


22.96 


26 


15 




4.77 


5.41 


1,663 


1,230 


518 


Grain spiral. 
Crooked. 




8 


53.8 


25.46 


28 


16 




4.62 


5.25 


1,536 


1,192 


422 




9 


55.8 


23.79 


42 


14 




4.93 


5.41 


1,888 


1,362 


538 






10 


53.3 


27.38 


46 


20 




4.38 


5.49 


2,115 


1,725 


608 


Grain slightly spiral. 




11 


38.1 


23.66 


24 


14 




5.65 


6.76 


1,518 


1,115 


416 


Crooked. 


Av'ge. 




62.3 


24.07 


32 


16 




4.95 


5.80 


1,750 


1,347 


529 




Douglas fir. . 


1 


89.1 


27.34 


20 


26 


68 


4.95 


5.45 


2,622 


2,180 


799 






2 


34.9 


25.22 


40 


24 


14 


5.33 


5.81 


2,870 


2,242 


596 






3 


91.6 


24.29 


23 


22 


52 


5.41 


6.05 


2,715 


2,438 


765 






4 


66.9 


25.33 


38 


14 


42 


5.60 


6.30 


2,200 


1,946 


718 


Grain spiral. 




5 


37.8 


28.57 


61 


24 


19 


4.93 


5.73 


2,358 


1,885 


676 


Do. 




6 


38.2 


27.08 


40 


28 


26 


6.84 


7.16 


2,664 


2,176 


856 






7 


42.9 


27.52 


45 


23 


31 


5.73 


6.45 


2,730 


2,330 


796 


Do. 




8 


34.8 


31.84 


26 


17 


38 


5.01 


5.57 


2,560 


2,030 


718 






9 


30.0 


30.10 


76 


25 


12 


5.89 


6.61 


2,545 


1,908 


789 


Do. 




10 


38.5 


27.77 


17 


28 


70 


5.09 


5.41 


2,560 


2,160 


865 


Do. 


Av'ge. 




50.5 


27.50 


39 


23 


37 


5.48 


6.05 


2,580 


2,130 


758 





22 



BULLETIN 77, U. S. DEPABTMENT OF AGRICULTURE. 



Table 11. — Data on individual crushing tests of green round mine props (nominal size, 
5-inch top by 6 feet long) — Continued. 









£§ 








Diameter. 


■33 

boO 


,£3*3 

bo'3 


| 






6 






a 
.9 


•a 

o 








o> .2 


CB 












Species. 


■ 




B+>£ 


u 

4> 


fct 


•6 






boS 


bo GO 

9.2 




Remarks. 




c 


9 

3a 

o 


ft? 3 


ft 

00 

be 

a 


s 

9 


8 

o. 


d 


3 


•9 « 


3 ;§ 
3 
•a 
o 






K 


5 


< 


5 


CQ 


GQ 


EH 


PQ 


S 


o 


s 


























1,000 






















Lbs. 


Lbs. 


lbs. 








Per 


Lbs. per 
ca. ft. 




Per 


Per 






per 


per 


per 








cent. 




cent. 


cent. 


In. 


In. 


sq. in. 


sg. in. 


sq. in. 




Bristle-cone 


1 


86.7 


30.78 


34 


22 


56 


4.25 


5.13 


1,474 


1,128 


390 


Crooked. 


pine. 


2 


109.0 


26.83 


32 


19 


56 


4.65 


5.50 


2,026 


1,590 


638 






3 


74.9 


30.86 


33 


18 


39 


4.80 


5.50 


1,364 


1,050 


453 






4 


106.1 


26.17 


41 


21 


36 


5.33 


6.40 


1,690 


1,435 


505 






5 


94.5 


29.57 


31 


22 


47 


4.52 


4.91 


1,480 


1,185 


525 






6 


56.1 


25.68 


31 


24 




3.98 


4.77 


1,400 


965 


446 


Crooked and unusu- 
ally knotty. 




7 


60.3 


28.95 


38 


16 


61 


4.46 


5.17 


1.760 


1,408 


574 


Do. 




8 


85.1 


25.83 


43 


23 


46 


5.17 


6.05 


1,828 


1,430 


464 


Grain slightly spiral. 




9 


101.0 


25.72 


32 


16 


43 


4.38 


5.16 


1,941 


1,528 


571 






10 


85.5 


26.39 


39 


16 


38 


4.30 


5.17 


1,610 


1,378 


516 




Av'ge. 


85.9 


27.68 


35 


20 


46 


4.58 


5.38 


1,657 


1,310 


508 




Western yel- 


1 


91.8 


22.67 


14 


14 




4.25 


5.25 


1,355 


1,128 


428 


Do. 


low pine 


2 


97.7 


23.09 


16 


19 




4.25 


5.00 


1,630 


1,410 


516 




(shipment 


3 


88.9 


22.52 


13 


14 




4.35 


5.10 


1,443 


1,211 


345 




A.) 


4 


92.0 


23.55 


14 


14 




4.70 


5.40 


1,269 


1,038 


451 


Crooked. 




5 


83.2 


22.48 


13 


15 




4.65 


5.60 


1,322 


1,060 


402 


Do. 




6 104.5 


22.33 


13 


12 




4.30 


5.13 


1,481 


1,172 


475 


Do. 




7 ,101.2 


22.71 


14 


IS 




4.78 


5.16 


1,518 


1,119 


438 






8 1 96.6 


23.62 


15 


15 




4.38 


5.41 


1,522 


1,262 


448 






9 89.3 


25.70 


15 


13 




4.14 


4.94 


i,681 


1,412 


512 


Grain slightly spiral. 




10 ;116. 1 




13 


15 




4.62 


5.01 


1,512 


1,193 


416 


Do. 






96.1 


23.18 


14 
32 


15 




4.44 


5.20 


1,475 


1,201 


443 










Western yel- 


11 1 81.1 


25.68 


14 




5.25 


6.15 


2,000 


1,570 


611 


Unusually knotty. 


low pine 


12 90.5 


23.22 


11 


14 




5.01 


5.73 


1,726 


1,320 


457 


Grain slightly spiral. 


(shipment 


13 1 83.0 


24.80 


24 


20 




5.65 


6.13 


1,668 


1,275 


448 


Do. 


B.) 


14 113.2 




19 


23 




5.33 


6.17 


2,055 


1,435 


491 






15 


54.8 


25.92 


19 


17 




5.49 


6.05 


1,682 


1,352 


478 


Grain spiral, crooked. 




16 


63.5 


21.58 


16 


13 




5.41 


6.05 


1,670 


1,132 


532 






17 


78.8 


24.62 


16 


15 




5.33 


5.97 


2,410 


1,883 


702 






18 


105.5 


24.78 


16 


12 




5.49 


5.81 


1,950 


1,269 


458 






19 


76.6 


26.20 


16 


14 




5.41 


6.05 


2,005 


1,392 


569 






20 


72.8 


26.28 


14 


13 




5.09 


5.89 


2,225 


1,865 


762 




Av'ge. 




82.0 


24.78 


IS 


16 




5.35 


6.00 


1,940 


1,450 


561 





ROCKY MOUNTAIN MINE TIMBERS. 



23 



Table 12. — Data on individual crushing tests of air-seasoned round mine props (nominal 
size, 5-inch top by 6 feet long). 









>>2> 








Diameter. 


sa 

tea 


6fl'3 

0.3 

i — i 


OS 






6 




■2° . 


1 


■3 
O 








a S 


a 












Species. 






■ass 




Be 


•a 
o 






■SJS 

3 15 ° 


taoto 
a a 


3^3 


Remarks. 




CD 
M 

•2 


.3 
o 


O MOJ 


be 

a 


S 

a 


P< 


A 
o 


3 




o 






tf 


a 


<1 


5 


CO 


OS 


frl 


« 


o 


o 


£ 


























1,000 






















Lbs. 


Lbs. 


lbs. 








Per 


Z6s. per 
cu. ft. 




Per 


Per 






per 


per 


per 








ceni. 




cent. 


cent. 


In. 


In. 


sq. in. 


sq. in. 


sq. in. 




L o d g epole 


1 


11.5 


24.58 


51 


21 


55 


4.85 


5.17 


3,910 


3,465 


890 


Grain spiral. 


pine (ship- 


2 


11.4 


24.46 


43 


22 


58 


4.77 


5.57 


3,992 


3,580 


875 


Do. 


ment A). 


3 


11.2 


27.96 


57 


18 


33 


5.17 


5.57 


4,770 


4,190 


1,194 


Do. 




4 


12.3 


24.16 


34 


20 


68 


5.09 


5.57 


3,340 


2,750 


954 


Do. 




5 


11.0 


25.83 


47 


19 


35 


4.77 


5.25 


4,640 


3,580 


1,031 


Do. 


Av'ge. 




11.5 


25.40 


46 


20 


50 


4.93 


5.43 


4,130 


3,513 


993 




Lodgepole 


6 


11.0 


28.14 


43 


26 


42 


4.38 


5.01 


5,100 


4,110 


1,198 


Do. 


pine (ship- 


7 


12.0 


27.72 


45 


26 




5.25 


5.57 


6,340 


4,980 


1,450 




ment B). 


8 


15.9 


23.42 


50 


26 


61 


5.17 


5.49 


4,980 


4,010 


1,135 


Do. 




9 


11.2 


29.52 


45 


20 


37 


4.01 


5.73 


6.190 


4,750 


1,452 


Do. 




10 


11.1 


26.58 


42 


17 


37 


5.25 


5.41 


5,230 


4,240 


1,175 


Do. 


Av'ge. 




12.2 


27.08 


45 


23 


44 


4.81 


5.44 


5,568 


4, 438 


1,282 




Alpine fir... 


1 


12.4 


20.24 


15 


16 




4.30 


5.41 


4,120 


3,165 


890 






2 


12.0 


22.88 


23 


12 




4.46 


5.33 


4,260 


3,875 


1,043 






3 


10.5 


20.38 


16 


9 




4.06 


5.09 


3,910 


3,550 


1,002 


Do. 






11.6 


21.17 


18 


12 




4.27 


5.28 


4,097 


3,530 


978 










Engelmann 


1 


11.7 


27.42 


41 


23 




4.62 


5.97 


5,560 


4,290 


1,321 


Do. 


spruce. 


2 


11.2 


28.10 


25 


13 




5.09 


5.49 


3.280 


2,555 


802 


Do. 




3 


11.0 


23.33 


29 


13 




3.50 


4.62 


3,742 


3,120 


1,021 


Do. 




4 


13.0 


24.00 


43 


22 




3.98 


5.25 


2,990 


2,410 


703 


Crooked. 




5 


13.7 


24.81 


50 


28 




4.30 


4.93 


4,540 


3,850 


1,196 


Grain spiral. 




6 


11.3 


23.86 


31 


20 




4.62 


5.33 


4,710 


3,822 


1,150 






7 


10.9 


21.78 


16 


12 




4.85 


5.49 


4,030 


3,030 


1,098 








11.8 


24.76 


33 


19 




4.42 


5.29 


4,122 


3,297 


1,042 










Douglas fir. . 


1 


11.9 


31.63 


76 


25 


31 


4.30 


4.62 


2,960 


2,340 


873 


Crooked; grain spiral. 




2 


11.5 


32.66 


47 


25 


39 


4.54 


5.39 


5,250 


4,450 


1,322 


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usually knotty. 




3 


11.6 


28.98 


65 


28 


39 


4.85 


5.17 


4,580 


3,465 


986 


Crooked; grain spiral. 
Grain slightly spiral, 




4 


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28.31 


30 


26 


60 


5.25 


5.41 


5,720 


4,240 


1,324 


























knotty. 




5 


13.0 


26.06 


28 


21 


37 


5.33 


6.05 


4,660 


3,590 


1,151 




Av'ge. 




12.3 


29.53 


49 


25 


41 


4.85 


5.33 


4,634 


3,617 


1,131 




Bristle-cone 


1 


12.5 


29.38 


40 


22 


42 


3.90 


4.54 


4,320 


3,512 


1,023 




pine. 


2 


12.6 


32.01 


45 


19 


49 


3.66 


4.30 


4,390 


3,420 


862 






3 


12.4 


36.46 


42 


20 




3.66 


4.22 


3,042 


2,280 


837 


Crooked; grain spiral. 




4 


12.2 


30.34 


35 


19 


68 


3.18 


4.30 


2,340 


2,013 


628 


Crooked. 




5 


12.2 


25.37 


30 


20 




3.98 


4.85 


3.415 


2,890 


779 




Av'ge. 




12.4 


30.71 


38 


20 





3.68 


4.44 


3,501 


2,823 


826 




Western vel- 


1 


10.5 


21.48 


16 


17 


21 


3.66 


4.80 


3,050 


2,470 


742 




low pine 


2 


11.1 


23.55 


15 


18 


88 


4.30 


4.62 


3,842 


3,310 


852 


Grain spiral. 


(shipment 


3 


11.9 


21.99 


14 


13 


95 


4.06 


4.85 


3,230 


3,625 


1,068 




A). 


4 


11.6 


25.50 


11 


19 


96 


3.50 


4.80 


5,330 


4,780 


1,146 






5 


13.4 


23.69 


15 


12 




4.14 


4.85 


3,370 


2,822 


626 








11.7 


23.24 


14 


16 


75 


3.93 


4.78 


3,764 


3,401 


887 










Western yel- 


6 


11.7 


26.30 


17 


12 




4.93 


5.57 


4,070 


3,250 


976 


Crooked. 


low pine 


7 


11.6 


24.03 


19 


17 




4.70 


5.25 


4,260 


3,690 


863 


Grain spiral. 


(shipment 


8 


13.0 


27.72 


31 


20 




4.93 


5.65 


4,420 


3,350 


1,160 




B). 


9 


11.5 


25.73 


13 


19 




4.93 


5.41 


4,790 


3,770 


1,115 


Do. 




10 


10.9 


23.64 


12 


14 




4.62 


5.33 


3,120 


2,270 


628 


Grain spiral, crooked. 


Av'ge. 




11.7 


25.48 


18 


16 




4.82 


5.44 


4,132 


3,266 


956 





24 



BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 



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30 



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ROCKY MOUNTAIN MINE TIMBERS. 



33 



MANNER OF FAILURE. 



The prop failures were quite uniform. Compression wrinkles 
occurred usually through one or more knots and, if the prop had a 
slight bend in it, the wrinkles were on the concave side at the point 
of greatest eccentricity. If this bend were at all prominent, tension 
often occurred and in several instances the prop separated in two 
parts as in the brittle cap failure. The influence of checks on the 
form of failures was quite noticeable in the dry props, the shortening 
of the props giving the check, if spiral, the appearance of " unwinding" 
as in the strands of a rope. Figure 6 shows this effect to some extent. 




Fig. 7.— -Method used in testing mine caps in bending. 



The failures of the green caps were quite uniform in character 
among the various species. Near or at the maximum load, com- 
pression took place on the upper surface between the loading points. 
The load fell off slowly, and if continued, failure by tension ultimately 
took place. The green Alpine fir caps, however, had a larger propor- 
tion of tension than compression failures, and the Douglas fir had 
approximately the same number of each. 

The dry caps, as far as could be detected by the eye, generally failed 
in tension near the center. Occasionally compression wrinkles oc- 
curred, but the failures were more often sudden, and some indicated 
brittle .material. There was no material difference in the failure of 
the different species. In the dry material the tension splinters often 
ended at a check, but it was not apparent that the type of failure or 



34 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTUEE. 

strength of the specimen was definitely influenced by the seasoning 
cracks, even when more or less spiral. 



The beam failures were similar to those occurring in the caps. 
The water-soaked material failed almost entirely in compression on 
the upper surface, the failure wrinkles becoming visible shortly before 
the maximum load was reached. Some of the green beams had a 
very large deflection, and the stress-strain curves were typically 
somewhat flat topped. The dry beams failed in tension, sometimes 
accompanied by failure in compression. 

o 




BULLETIN OF THE 



No. 78 




Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
May 18, 1914. 

(PROFESSIONAL PAPER.) 

THE SO-CALLED TOBACCO WIREWORM IN 
VIRGINIA. 

By G. A. Runner, 
Entomological Assistant, Southern Field Crop Insect Investigations. 

INTRODUCTION. 

For the study of insects injurious to tobacco the Bureau of Ento- 
mology during the last four summers has maintained a temporary 
field station at Appomattox, Va. Work of this station has been 
under the direction of Mr. W. D. Hunter, in Charge of Southern 
Field Crop Insect Investigations, and more immediately under the 
supervision of Mr. A. C. Morgan. Laboratory quarters were fur- 
nished by the Tenth Congressional District Agricultural School. 
The results of investigations of the tobacco Crambus (Crambus cali- 
ginosellus Clem.) are given in this bulletin. 

The work in Virginia was in cooperation with the State experiment 
station and the Bureau of Plant Industry of the U. S. Department 
of Agriculture. Through an agreement with the cooperators, the 
Bureau of Entomology was furnished all data pertaining to the rota- 
tion of crops grown in connection with tobacco, and the plats of the 
several tobacco stations in the State were placed at the disposal of 
the agent in charge, for inspection and experiment. The records 
of these stations, extending over a series of years, are of great value 
in determining the crop rotations and cultural methods of control 
best adapted to the special conditions to be dealt with in different 
tobacco sections. 

The experimental work with tobacco in Appomattox County, Va., 
was begun by the Bureau of Soils in 1904. The work has since been 
conducted cooperatively by the Bureau of Plant Industry and the 
Virginia experiment station. Since the first, owing to the work of 

i Throughout the tobacco-growing sections of Maryland, North Carolina, and Virginia the larvae of the 
tobacco Crambus are generally known as " wireworms." They are also known in other sections as " tobacco 
wireworms," "budworms," "corn worms," "stalk worms," "heart worms," "cutworms," "stem worms," 
"root web worms," and "screw worms." In parts of Tennessee and Kentucky the larvae are commonly 
called "screw worms." The term "wireworm" is also applied, as in other sections, to the true wire- 
worms (larvae of Elateridae), which the Crambus larvae in no way resemble. 

Note.— This bulletin is descriptive of an insect enemy of tobacco and corn. Of especial interest in 
the eastern tobacco and corn districts. 

30183°— Bull. 78-14 1 



2 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

the tobacco Crambus, great difficulty has been encountered, in 
many of the experiments, in getting the perfect stand of plants so 
essential for comparative tests. This led to a study of the life his- 
ton T of the insect and of the somewhat extensive cultural experi- 
ments by the Bureau of Entomology aimed at its control. The 
effect of certain crop rotations in reducing injury from the tobacco 
Crambus was noticed during the early progress of the cultural in- 
vestigations b}^ Mr. E. H. Mathewson, Crop Technologist of the 
Bureau of Plant Industry, to whom the writer is indebted for sug- 
gestions concerning the cultural methods of control undertaken by 
the Bureau of Entomology. 

GENERAL HABITS AND ECONOMIC IMPORTANCE OF THE GROUP 
TO WHICH THE TOBACCO CRAMBUS BELONGS. 

The larva? of insects included in the family Crambidae, to which 
the tobacco Crambus belongs, feed mainly on the grasses (Graminese), 
although some of them subsist on plants of other families. Many 
construct tubular, web-lined galleries near the roots of the plants on 
which they feed, and some bore or tunnel into the roots or stems; for 
this reason they have been named "root webworms." The moths, or 
adults, are medium or rather small in size, with brown, yellow, or 
white colors prevailing. Many species have metallic markings on 
the forewings, which are comparatively long and usually narrow. 
When at rest the forewings are rolled around the body and conceal 
the hind wings, which are folded beneath. This gives the body the 
appearance of a tiny cylinder, and accounts for the term "close- 
wings." The species are widely distributed over the globe, but are 
apparently most numerous in temperate climates. In North America 
comparatively few are known, and the majority of these belong to 
the genus Crambus, in which Dr. H. G. Dyar 1 catalogues 60 species. 

Moths of the genus Crambus fly mostly on dark afternoons and 
during the early part of the night. They are more common in open 
fields. When disturbed they make short erratic flights, rarely 
flying more than a few rods at a time. They usually alight head 
downward on the stems of plants, and their color often harmonizes 
so perfectly with their surroundings that they can with difficulty be 
seen. Most of the species are single-brooded; but as the moths of 
different species emerge successively throughout the season, one or 
more of the latter are present in most localities from spring until 
late fall. Though various species of Crambus are common in most 
localities, they seldom attract much attention unless some important 
crop is attacked. This is due (1) to the fact that the moths are 
small and inconspicuous, (2) to the underground feeding habits of 
the arvse, land (3) to the fact that damage from different species is 
distributed throughout the growing season. 

1 I>yar, Harrison G. A List of North American Lepidoptera * * *. U. S. Nat. Mus. Bui. .52, pp. 
404-410, 1902. 



THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 6 

The principal species of the genus of economic importance in this 
country are: Crambus caliginosellus Clemens, which attacks tobacco 
and corn; C. vulgivagellus Clemens, an enemy of corn, wheat, rye, 
and grasses; C. trisectus Walker, an enemy of grasses, oats, and corn; 
C. laqueatellus Clemens, which attacks corn and oats; C. zeellus Fer- 
nald, C. luteolellus Clemens, and C. mutabilis Clemens, enemies of 
corn; and C. hortuellus Hiibner, which is injurious to the cranberry. 
The wide distribution of several of these and their great capacity for 
injury give them rank as species of considerable economic impor- 
tance. Damage by them to cultivated crops is, in most cases, the 
result of unusual conditions. Their range of food plants is not 
large, and the larvae are inclined to remain in or near one place. 
The moths frequent the weedy fields, pastures, or meadows which 
contain the natural food plants of the larvae, and the greater num- 
ber of eggs are deposited in such localities. When such land is 
plowed up the larvae are forced to live on other than their natural 
food plants. With crops such as corn and tobacco this means a 
concentration of larvae from many of the wild or natural food plants 
to the comparatively few cultivated plants. 

ECONOMIC IMPORTANCE OF THE TOBACCO CRAMBUS. 

The tobacco Crambus (Crambus caliginosellus Clem.) occurs in 
most, if not all, of the tobacco-growing districts of the Eastern 
States, but it seems to be most destructive in certain sections of 
Maryland and Virginia. It is especially destructive in the famous 
"dark-tobacco district" of the Piedmont section of middle Virginia, 
although found in all sections of the State in which tobacco is 
grown. In Virginia the damage to the tobacco crop alone from 
the insect is estimated to average at least $800,000 annually. 

At the Virginia tobacco experiment, stations, at Appomattox, 
Bowling Green, and Chatham, injury has been recorded for a num- 
ber of years. The reduction in value of the crop has been great, 
amounting to about 14 per cent annually, through failure to secure 
an early stand of plants. At the Appomattox Station, in one of 
the experimental fields, there was a loss in 1910 amounting to 
about 27 per cent. In 1911 there was still greater loss in some 
of the plats. In many fields in the county fully one-half of the 
plants were attacked, making several replantings necessary. At 
the Chatham Station in 1909 there was an estimated decrease in 
the value of the crop amounting to about $15 per acre. 

In 1912 considerable damage occurred to tobacco in Montgomery 
County, Tenn., and in Christian and Todd Counties, on the south- 
ern border of Kentucky, growers in a number of instances report- 
ing fully 40 per- cent of the plants destroyed. 



BULLETIN T*-:, U. S. DEPARTMENT OF AGRICULTURE. 



The insect has for many years been a serious pest to tobacco and 
corn in Maryland. W. G. Johnson, formerly State entomologist, 
recorded the species as extremely abundant and destructive in 
Prince Georges, Cecil, Kent, Queen Anne, and Dorchester Coun- 
ties in 1897, and reported damage in various parts of the State in 
1898, 1899, and 1900, many fields of young corn being almost com- 
pletely destroyed. 

M. H. Beck with mentions it as injurious to corn in Delaware, and 
John B. Smith has recorded injury to corn in New Jersey. 

ORIGIN AND DISTRIBUTION. 

Crambus caliglnosdJus has been recorded only from North Amer- 
ica. Its preference for the naturalized buckhorn plantain and ox- 
eve daisy as food plants, however, points to the possibility that it 
has been introduced from Europe. 

In literature the recorded distribution of the species is as follows: 
Ontario (Saunders, Felt, and Fernald); New York (Grote, Felt, and 

Fernald); Delaware (Beckwith); New 
Jersey (Smith); Maryland (Johnson 
and Howard); Massachusetts, Penn- 
sylvania, District of Columbia, North 
Carolina, Illinois, and Texas (Fer- 
nald); Virginia (Mathewson, Ander- 
son, and Runner); Ohio (Gossard). 

In collections in the National Mu- 
seum are specimens from the follow- 
ing localities: Washington, D. C. 
(August Busck); Plummers Island, 
Md. (H. S. Barber); Plainfield, N. J. 
Pittsburgh, Pa. (H. Engel); Clarksville, Tenn. 
Chapel Hill, Tenn. (G. G. Ainslie); Vienna, Va. 




Fig. 1.— Adult, or moth, stage of the tobacco 
Crambus. or " wireworm" f Crambus cali- 
ginosellus). Enlarged. (Original.) 



(F. O. Herring); 
(A. C. Morgan); 
(R. A. Cushman). 

Records of the Bureau of Entomology show the insect to be present 
in Pennsylvania, Delaware, Maryland, Virginia, West Virginia, North 
Carolina, South Carolina, Ohio, Tennessee, and Kentuck} T . 

These records indicate a wide distribution, but as most reports of 
injury to cultivated crops come from certain portions of the Eastern 
States it is probable that severe injury occurs only in localities where 
natural food plants are exceedingly abundant, and where crops 
subject to injury are planted at the time the larva? are completing 
their growth and are in their most active feeding stage. 

SEASONAL HISTORY. 

The moths ('fig. 1 ) emerge during summer, the heaviest emergence 
occurring at Appomattox, in central Virginia, during the first and 
second weeks iii August. The earliest emergence takes place during 



THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 



the latter part of June, but moths are not abundant until about the 
third week in July. From this time their numbers gradually increase 
until about the second week in August, when they are exceedingly 
numerous, at times appearing almost in swarms in weedy fields when 
disturbed. From the middle of August there is a rapid decrease and 
after the 1st of September only an occasional one can be found. 
Table I gives dates of emergence of moths from some of the field 
cages at Appomattox in 1910. 

Table I. — Emergence of moths of the tobacco Crambus in outdoor rearing cages at Appo- 
mattox, Va., 1910. 



Larvae col- 
lected— 


Food plant on 
which found. 


Moth 
emerged — 


Larvae col- 
lected— 


Food plant on 
which found. 


Moth 
emerged — 


1910. 




1910. 
July 2. 
July 21. 
July 22. 
Aug. 3. 
July 3. 
July 14. 
July 22. 
July 23. 
July 26. 
Aug. 1. 
July 29. 


1910. 

June 26 

Do 

Do 

Do 




1910. 

July 18. 


Do 


do .. 


Wild carrot 

Tobacco 


Aug. 13. 


Do 


do 


Aug. 6. 


Do 


do... 


do 






do 


June 28 

Do 

Do 

Julyl 

Do 

Do 


Plantain 


July 14. 


Do 






Aug. 15. 


Do 

Do... 


Senecio 


Aster (stickweed) . 


Aug. 7. 
July 29. 










Do 






July 27. 


Do... 
















The females die soon after egg laying is finished. There is appar- 
ently only one generation a year, the eggs hatching in summer and 
the larvae completing their growth during the follow- 
ing year. The greater number of larvae are in the pupal 
stage during the first halt of July. 

DESCRIPTION. 

THE EGG. 

The egg (fig. 2) is creamy white when first deposited, but grad- 
ually assumes a pinkish shade, which deepens to orange rufous 
before hatching. The average length is 4 mm. and the diameter 
0.32 mm. It is regularly oval, with the ends slightly truncate, 
and has a polished appearance. There are about 18 longitudinal 
carinee and numerous transverse striae. 

THE LARVA. 

FIRST INSTAR. 

When first hatched, the body of the larva is semitransparent, and the alimentary 
canal can be plainly seen. The outline of the body, when seen from above, is almost 
triangular. The larva is white, or pale yellowish white, and about 1 mm. long, with 
a few scattered, light-colored hairs on the head and body. The head shield measures 
0.15 mm. in width, is yellowish brown, and moderately bilobed, with the clypeus 
attaining the apical third. The cervical shield is tinged slightly with brownish. 
Five pairs of prolegs occur on the 7th to 10th segments, inclusive, and on the 13th 
segment. 

LAST INSTAR. 

The full-grown larva (figs. 3, 4) is about 15 mm. long, and yellowish white, with a 
tinge of pink dorsally. The hairs of the body are slender, brownish, and set on large 
fuscous tubercles. The head shield measures 1.2 mm. in width, and is pale yellowish 



Fig. 2.— The to- 
bacco Crambus: 
Egg. Greatly 
enlarged. (Origi- 
nal.) 



6 



BULLETIN 78, U. S. DEPARTMENT OP AGRICULTURE. 




Fig. :-i. — The tobacco Crambus: Full-grown larva, or "wireworm. 
Much enlarged. (Original.) 



brown, flecked with darker brown. The cervical shield is distinct, shining, yel- 
lowish brown, tinged with fuscous, and bears 12 hairs in two transverse equal rows. 
The anal shield is pale fuscous. About the middle of abdominal segments 3, 4, 5, 
and 6, and slightly above the spiracles, is a series of distinct, dark fuscous, chitinous 
areas about the size and shape of spiracles, one to each segment. 

The arrangement of the tubercles is as follows: Beneath the anterior margin of the 
cervical shield is a tubercle bearing two hairs. The mesothorax above bears eight 

setigerous tubercles on the 
anterior margin, each, ex- 
cept the lateral tubercle, 
with two hairs. Posteriorly 
it is provided with three bare 
tubercles, of which the medi- 
an is narrow and transverse. 
The metathorax is armed, 
as is the mesothorax. Each 
abdominal segment above the spiracles bears two transverse rows of four tubercles 
each. The anterior dorsal pair are subquadrate, with the posterior lateral angles 
strongly rounded. The posterior dorsal pair are oblong, transverse, about half as 
long as the anterior, with the posterior lateral angles strongly rounded. The anterior 
lateral tubercles are supraspiracular, irregularly quadrate, with the lower margin 
produced diagonally behind the spiracle, emarginate at the spiracle and before the 
impressed area on segments 3, 4, 5, and 6. The 
corresponding tubercle on segment 8 has the pro- 
duced portion isolated and is placed anterior to the 
spiracle. The posterior lateral tubercles are trans- 
verse, elongate, and somewhat oblique. 

Abdominal segments 1 to 7 each bear a minute 
spinule anterior to and nearly equidistant from the 
spiracle and the supraspiracular hair. 

The legs are pale brown, the maxillary palpi 
brown, and the mandibles brownish fuscous at 
apices. 

The color of larvae collected from, differ- 
ent food plants varies considerably, this 
being merely an effect of the color, whether 
light or dark, of the food in the alimentary 
canal. Larvae collected from corn are considerably lighter than those 
collected from tobacco. 

THE PUPA. 

The pupa (fig. 5) measures about 8 mm. in length and 2 mm. in greatest width. 
The general color is dark brown, or pale yellowish brown when newly transformed, 
with the appendages and segments marked with dark brown. The head is blunt, 
with a median apical emargination . The tips of the wings are rounding on abdominal 
segments; the margin of the inner wing is visible over segments 2, 3, and 4. The 
spiracles are not prominent, the first three pairs being set on blunt tubercles. The 
cremaster is transversely rounded oblong, with a lateral bristle near the apex. 

THE ADULT, OR MOTH. 

Expanse of wing, 13-25 mm. Head, palpi, and thorax dark fuscous, sprinkled with 
gray scales. Fore wing dark fuscous, sprinkled with brown or yellowish, and fre- 
quently with a few gray scales; median line dark brown, often edged with white, aris- 




Fig. 4. — The tobacco Crambus: Head 
of larva. Greatly enlarged. (Origi- 
nal.) 






THE SO-CALLED TOBACCO WIEEWOEM IN VIRGINIA. 



ing a little beyond the middle of the costa, extending outward, forming a very acute 
angle, thence backward across the end of the cell to the hind margin, a little beyond 
the middle, and giving off an outward angle on the fold. Subterminal line dark brown, 
edged outwardly with dark lead-colored scales, and frequently dentate along the first 
part of its course. It arises from the costa about half way between the median line and 
the apex, extending down to a point beyond the end of the cell, where it forms an out- 
ward angle, thence to the hind margin, a little within the anal angle, giving off an 
inward angle on the fold. This angle is frequently connected along the fold with the 
outward angle of the median line; terminal line dark brown, rather indistinct. The 
lines are often obliterated more or less, especially the median. Fringes dark leaden 
gray. Hind wings dark fuscous; fringes a little lighter. [Fernald, 1896.] (See fig. 1.) 

The moths vary somewhat in color and distinctness of markings, 
some specimens being much darker than others when first trans- 
formed. In the hind wing the frenulum is a single short spine in the 
male. In the female the frenulum is more slender and is very finely 
divided at the tip. In the female of a number of other 
species of this genus the frenulum consists of two dis- 
tinct spines. 

LIFE HISTORY. 

HABITS OF THE MOTHS. 

The moths fly during late afternoon, on dark days, 
and during the early part of the night. They are 
attracted to light, but in comparatively small num- 
bers considering their great abundance at certain 
times. The majority of the females collected at trap 
lights are those which have deposited their eggs. 
During the day, when disturbed, they make short, 
erratic flights, usually alighting head downward on 
the stems of weeds and grasses, their tightly closed 
wings and grayish color making them very inconspic- 
uous. As with other members of the genus Crambus, their long palpi, 
extending parallel to the stem of the plant on which they are at rest, 
help to make the outlines of the body conform to the appearance of 
that part of the plant. 

OVIPOSITION. 

When the m®ths were confined in cages, the eggs were deposited at 
random over the surface of the ground. They seemed dry when 
deposited, rolled about easily, and did not adhere to papers placed 
over the soil in the rearing cages, or to glass when females were con- 
fined in large test tubes. Normally the eggs are doubtless placed in 
the same manner, for on two occasions eggs were found on the upper 
surface of leaves of sweetbrier lying flat on the ground. Egg laying 
commences shortly after the moths emerge. Fertile eggs were not 
obtained from moths reared in the cages. 




Fig. 5. — The tobacco 
Crambus: Pupa. 
Much e n la r g e d . 
(Original.) 



8 



BULLETIN 78, l'. S. DEPARTMENT OF AGRICULTURE. 



Records obtained from a large number of females, collected in the 
fields and placed in separate cages for egg deposition, show the average 
number of eggs laid to be 177. Among the records obtained at Appo- 
mattox. Ya., during 1910, are those in Table IT. 



Table II. — Number of eggs laid by the tobacco ('nimbus, Appomattox, Ya.. 1910. 



No. 

of fe- 
male. 


Moth colletled. 


Period of ovipo- 
sition. 


Num- 
ber 
eggs 
laid. 


No. 
of fe- 
male. 


Moili collected. 


Period of ovipo- 
sit ion. 


Num- 
ber 

eggs 
laid. 


1 


1910. 

July 8 

do 

do 


1910. 
July 9-13 .• 


21S 


10 
11 
12 
13 
14 
15 
10 
17 


19111. 

Aug. 11 

...^.do 

Aug. 14 

do 

do 

do 

do 


1910. 

Aug. 12-15 

Aug. 12-10 

Aug. 15-20 

Aug. 15-18 

Aug. 10-20 

Aug. 16-19. . 


83 


2 
:5 


do 

July 9-14 


08 
271 


203 

218 


4 


July 10 


July 11-14 


156 

211 
310 
287 
77 
301 


194 


5 
6 


July 12 

July 17 

do 

July 25 

Aug. 11 


July 13-18 

July 18-22 


222 
91 




July IS 23 


Aug. 16-21 

Aug. 16-18 


238 


8 
9 


July 20-30 

Aug. 12-10 


03 



Several individual females laid over 300 eggs, and over 300 were 
obtained in several instances by dissection. It is probable that the 
average number of eggs deposited normally is above rather than 
below the average obtained in the cages, as some of the moths may 
have laid eggs before capture, although records were not included 
from moths which deposited eggs within 12 hours after capture. 1 

The period of oviposition lasts from 3 to 5 days, the females dying 
shortly after egg laying is finished. The records of two females col- 
lected in the field on August 10, 1910, are given in Table III. 

Table III. — Rate of oviposition of the tobacco Crambus, Appomattox, Va.,1910. 



Female No. I. 



Num- 
ber of 
eggs de- 
posited. 



Aug. 11. 
Aug. 12. 
Aug. 13 . 
Aug. 14. 
Aug. 15. 



1910. 



Total. 



Date. 



1910. 

Aug. 10 

Aug. 11 

Aug. 12 

Aug. 13 

Total 



Num- 
ber of 
eggs de- 
posited. 



DURATION OF THE EGG STAGE. 

The period of incubation was found to be from 5 to 9 days, the 
greater number of eggs hatching about the sixth day at ordinary 
summer temperatures. 

i The dissection of 17 females of Crambus caliginosellus collected in the field during the third week in 
July, 1912, showed that 8 of the 17 collected contained more than 100 eggs. The number of eggs (mature 
or nearly mature) found in the H moths containing more than 100 eggs was as follows: 143, 322, 127, 290, 
807, 124,342,208. 



Bui. 78, U. S. Dept. of Agnculto 



Plate I. 




Fig. 1.— Injury of the Tobacco Crambus, or "Wireworm," to Tobacco. 




Fig. 2.— Injury of the Tobacco Crambus, or "Wireworm," to Corn. 
WORK OF THE TOBACCO CRAMBUS. 



Bui. 78, U. S. Dept. of Agriculture. 



Plate 




&£%£* 









4 ^;-tv v 




Fig. 1.— Poor Stand of Tobacco Resulting from Planting on Weedy Land. 
Note heavy growth of oxeye daisy in part of field not in tobacco. 




Fig. 2.— Wild Carrot and Other Weeds in Field of Red Clover. 
Injury from the " wire worm" occurs when land of this kind is planted in tobacco or corn. 



RELATION OF WEEDY LAND TO INJURY BY TOBACCO CRAMBUS. 



THE SO-CALLED TOBACCO WIREWOEM IN VIRGINIA. 9 

Table IV. — Duration of egg stage of the tobacco C'rambus, Appomattox, Va., 1910. 



Lot 
No. 


Eggs laid— 


Eggs hatching — 


Incuba- 
tion 
period. 


Lot 
No. 


Eggs laid— 


Eggs hatching— 


Incuba- 
tion 
period. 


1 


1910. 

July 7 

July 11 

July 12 

July 13 

July 25 

July 26 

Aug. 11 


1910. 
July 12 


Dai/s. 

5 
8-9 

7 
6-7 

6 
6-7 
5-6 


8 
9 
10 
11 
12 
13 


1910. 

Aug. 12 

Aug. 13 


1910. 

Aug. 17-18 

do 


Days. 
5-6 


2 


July 19-20 

July 19 


4-5 


3 


Aug. 14 

Aug. 15 

Aug. 16 

Aug. 17..- 


Aug. 19-20 

Aug. 20 


5-6 


4 


July 19-20 

July 31 


5 


5 


Aug. 21-22 

Aug. 23-24 


5-6 


6 

• 7 


Aug. 1-2 

Aug. 16-17 


6-7 



HABITS OF THE LARVAE. 



NATURAL FOOD PLANTS. 



Larvae of the tobacco Crambus have been found feeding on the 
following wild plants : 



Buckhorn plantain (Plantago lanceolata). 
Oxeye daisy (Chrysanthemum leucanthe- 

mum). 
Wild aster or "stickweed"' (Aster eri- 

coides and other species). 



Wild carrot (Daucus carota). 
Sheep sorrel (Rumex acetosella). 
Senecio (Senecio jacobgea) . 
White-top (Erigeron annuus and other 
species) . 



The first two plants named, the buckhorn plantain and the oxeye 
daisy (PI. II, fig. a), were found to be the main food plants of the 
larvae in the localities studied. The eradication or control of these 
weed pests, therefore, will result in comparative immunity from loss 
by this insect. Both species of plants have been found heavily 
infested in many localities in widely separated sections. During 
early spring the plantain seems to be the preferred food plant; later 
a heavy infestation occurs on both plantain and daisy. 

On July 8, 1910, 23 out of 25 oxeye daisy plants examined in a 
weedy field were infested, there being a total of 69 larvae about the 
roots. As many as 20 larvae have been collected from one plant of 
the oxeye daisy. 

In tobacco-growing sections of Tennessee and Kentucky white-top 
is a frequent food plant. 

When meadows are plowed up and planted to tobacco there is 
frequently serious injury from the "wireworms." (See PL II.) 
Where such injury has occurred the weeds mentioned above have 
invariably been found abundant in the sod, which explains the pres- 
ence of the "worms." Injury has not been observed where there had 
been previously a clean growth of grass or clover. Attempts to rear 
adults from larvae confined in field cages containing only timothy and 
clover resulted in failure, although the larvae lived for a considerable 
time without other food. 

30183°— Bull. 78—14—2 



10 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 



INJURY TO TOBACCO. 



The tobacco is attacked soon after planting, and feeding by the 
larvae continues until the first or second week of July. The larvae 
usually commence operations just below the surface of the ground, 
although newly set plants are frequently attacked at the "bud" or 
whorl of terminal leaves. As feeding continues the larvae, especially 
the smaller ones, frequently enter the stalk and tunnel upward, the 
burrows often extending to the base of the first leaves and some dis- 
tance above the surface of the ground. (See PI. I, fig. a.) When not 
feeding the "worms" are found about the base of the plant, usually 
in cylindrical, web-lined galleries, which extend from the plant, often 
for several inches, beneath the surface of the soil. 

Injured plants may usually be detected by their stunted or wilted 
appearance, which is more noticeable during hot, dry weather. The 
stems are in some cases entirely cut off, although this form of injury 
is rather unusual. 

Although plants often partially recover they do not obtain full 
growth, and it is evident that the presence of many dwarfed or 
stunted plants must result in very materially lessening the yield. The 
value of the crop is greatly decreased also, owing to the large proportion 
of late plants resulting from replanting. Early planted tobacco is 
usually better in quality than the late planted, it being finer and 
more elastic, curing better, and consequently bringing higher prices. 
The attacks of the larvae often make it necessary to reset the crop 
several times, and a good stand of plants is not secured, if at all, until 
too late to make the crop as profitable as it should be. 



INJURY TO CORN. 



Owing to its wide distribution in the Eastern States the tobacco 
Crambus is a serious pest to the corn crop. Injury has been noted 
in many localities where little tobacco is grown, and it is probable 
that damage to corn amounts to even more than that to tobacco. 
As with tobacco, injury is most severe when corn is planted on land 
which has been in weedy pasture or meadow previously, or when 
planted on land which has not been under cultivation for a number 
of years and on which there has been a rank growth of weeds. On 
such land it is usually difficult to secure a satisfactory stand of corn, 
and the yield is greatly reduced. (See PI. I, fig. b.) In central 
Virginia many fields under observation were replanted several times, 
and owing to the lateness of the season when a stand was secured 
the value of the crop was decreased fully one- third. Corn or tobacco 
planted on newly-clearea land seldom suffers injury from the Crambus. 
Since the species of weeds which are the natural food plants of the 
insert do not thrive in woodland, the larvae are not present when the 
crop is planted. 



THE SO-CALLED TOBACCO WIKEWORM IN VIRGINIA. 11 

The larvae attack the young corn near the surface of the ground and 
burrow into the base of the stalks, the outer portion of the stalk being 
frequently girdled. If the stalks are small when attacked, they are 
either killed or so stunted or dwarfed that they never fully outgrow 
the injury, and produce little or no grain. Much of the corn is 
attacked just after the seed has sprouted. The larvae frequently 
burrow into the folded leaves as the corn is coming through the 
ground. As the leaves unfold they show transverse rows of holes. 
When the stalks reach a height of a foot or more comparatively little 
damage is done. Several larvae are frequently found about the roots 
of a single stalk, and as many as 22 have been collected from a single 
hill of corn. In wet weather injury is not apt to be so severe} as 
the plants are then more vigorous and the weeds, which furnish suit- 
able food for the worms, more plentiful. As with tobacco, corn is 
attacked when the natural food supply of the "worms" is cut off. 

GENERAL FEEDING HABITS. 

The feeding habits of the "wireworm" on plants other than corn 
and tobacco are, in a general way, the same. There is a tendency to 
girdle soft-rooted plants, such as plantain and the wild carrot (PL II, 
fig. b) , and the larvae are often found embedded in cavities where they 
have fed. The buckhorn plantain (Plantago lance olata) is frequently 
killed where the infestation is heavy. A marked preference is shown 
for the natural food plants, and farmers, when the larvae are especially 
troublesome, frequently take advantage of this fact by cultivating at 
first only one round to the row, allowing the weeds to grow in the 
center of the row until the corn or tobacco has become better estab- 
lished. In a plowed field the larvae, if they have not finished feeding, 
concentrate about plantain, daisy, and stickweed {Aster spp.) which 
have not been killed by plowing. 

The larvae do not seem to travel far in search of food, as was 
ascertained by plowing badly infested land adjoining fields of corn 
and tobacco. When disturbed the} 7 crawl actively in either direc- 
tion, and they will often spin a slender silken thread by which they 
may be suspended. They feed most actively at night. 

THE YVVJE. 

The larvae pupate in the soil near the plants on which they feed. 
Before pupation there often seems to be a rather long period during 
which the larvae remain inactive in their cells. The pupal cells are 
usually found at a distance of from 1 inch to 6 inches from the base 
of the food plant and at a depth varying from one-half inch to 4 
inches. 

Table V shows the depths at which pupae were found about various 
food plants in soils varying from hard stiff clays to loose sandy loams. 



12 



BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 



Table V. — Depth at which pupation of the tobacco Crambus takes place, Appomattox, 

]'<!., 1910. 



Date. 


Character of soil. 


Food plant. 


Depth. 

Inches. 
2.5 
3.5 
1 

. 5 
4 


Date. 


Character of soil. 


Food plant. 


Depth. 


1910. 
Julv 9 


Red clay Tobacco 


1910. 
Julv 11 
Do.... 




Tobacco 

Corn 

Daisy 

Plantain . . . 
Daisy 


Indus. 

1 


Co... 


do.'. 


2.5 


Do... 


do 


Plantain... 
do 


Do.... 
Do.... 

Do.... 


Sandy loam 

Red clay 




Do . 




1 


Do 


Black loam 

Gray sandy loam.. 


1 »aisy 

Tobacco 


do 


1.5 


July 11 









Numerous measurements made at different times gave results very 
similar to those shown above. The average depth at which pupation 
takes place was found to be about 1.5 inches. 

The cells averaged about 9.5 mm. in length and 4.5 mm. in width 
(inside measurements). The lower portion of the cell is usually 
somewhat larger than the upper portion, the pupa lying in the larger 
end of the cell in convenient position for its egress. The cells are 
extremely fragile and are easily broken when removed from the soil. 
They are constructed of fine particles of earth and grains of sand in- 
terwoven with a silky weblike material. The walls are thin and the 
interior surface quite smooth. 

The pupal period, as shown in Table VI, lasts from 10 to 15 days. 

Table VI. — Pupal period of the tobacco Crambus. Appomattox, Va., 1911. 



Larva? 
collected — 


Pupated — 


Moth 
emerged — 


Num- 
ber of 
days. 


Larvae 
collected — 


Pupated — 


Moth 
emerged — 


Num- 
ber of 
days. 


1911. 
June l^ 

Do 

June 20 

Do 

Do 

July 1 


1911. 

July 7-10. . . . 
July 10-11... 
Julv 7-9 

July 12 

Julv 15 

July 28-31... 


1911. 

July 21 

do 

July 22 

July 26 

Aug. 10 


\ 
11-14 
10-11 
15-17 
10 
11 
10-13 


1911. 

Julvl 

Julv 12 

Do 

Do 

Do 

Do 


1911. 

July S 

Aug. 1-3.... 

July 15 

July 28-31. . . 

Aug. 1-2 

Aug. 1 


1911. 

July 22 

Aug. 15 

Aug. 1 

Aug. 10 

Aug. 15 

Aug. 12 


14 
12-15 

15 
10-13 
13-15 

12 



Table VII shows the duration of the period during which the 
insect is in the pupal cell before and after pupation. 

Table VJ I. — Duration of pre pupa I and pupal periods of the tobacco Crambus at Appo- 
mattox, Va.. 1911. 



N'uin- 
ber of 
record . 


Larvae ceased 

feeding— 


Moth 

emerged — 


Days. 


Num- 
ber of 
record . 


Larvae ceased 
feeding— 


Moth 
emerged — 


Days. 


1 


Kill. 
June 18 


1911. 
July 10 

Julv 16 

Julv 18 

Julv 20 

Julv 19 


22 1 

27 

28 

15 

17 

16 


8 
9 
10 
11 


1911. 
July 9 


1911. 
Aug. 1 


23 


2 


do 


July 11 


July 24 

July 29 


13 


:i 


do 


Julv 13 


16 


4 


Julv 3 


Julv 14 

...do.... 


20 


5 


. .do ... 


July 29 


15 


6 


...do 













THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 13 

NATURAL ENEMIES. 

In spite of its long larval period the tobacco Crambus does not 
seem to be largely parasitized, at least during the later stages, this 
being due presumably to the subterranean habits of the larvae and 
the protection afforded by the loose web in which they usually lie 
when not feeding. Nevertheless parasitic and predaceous enemies 
are doubtless factors in keeping the insect in check. The vast num- 
ber of newly hatched larvae as contrasted with the number found 
later in the season shows that comparatively few survive the earlier 
larval stages. This reduction is due in part to various natural ene- 
mies the exact or relative importance of which it is hard to estimate. 

Various carabid beetles have been observed to feed on the larvae. 
Among them were Calosoma calidum Fab. and Chlsenius tomentosus 
Say. Adults and larvae of Harpalus (Harpalus pennsylvanicus De G. 
and H.faunus Say) were observed to be very abundant about roots 
of oxeye daisy and plantain which were heavily infested with 
Crambus larvae. As the species of Harpalus are known to be gen- 
eral feeders, they were thought to feed on the larvae of the Crambus. 
The adults, when confined in tubes with larvae, occasionally fed on 
them. 

Spiders of several species were observed to feed on the larvae, and 
large numbers of the moths are captured in spider webs in weedy 
fields. 

Ants also occasionally attack the larvae. An ant found carrying 
a partly grown larva at Chatham, Va., was examined by Mr. Theo- 
dore Pergande and found to be a species of Solenopsis. 

W. G. Johnson, in Maryland, reported the rearing of an undeter- 
mined hymenopterous parasite from the larvae. No parasitic 
Hymenoptera were secured from the rearing cages at Appomattox, 
although large numbers of larvae were confined. 

Several Diptera were observed in cages containing larvae on vari- 
ous occasions, but actual proof of parasitism was not obtained, 
although a species of Phoridae was secured from tubes containing 
larvae under circumstances pointing strongly to parasitism. 

In the National Museum are specimens of a hymenopterous para- 
site, Perisemus prolongatus Pro v., labeled as reared from larvae of 
Crambus caliginosellus from La Fayette, Ind. The record is doubt- 
ful, however, as the notes concerning the specimens in the files of 
the Bureau of Entomology clearly refer to a different species of 
Crambus as the host. 

Birds are a factor in keeping the tobacco Crambus in check. Two 
species, the quail (Colinus virginianus) and the kingbird (Tyrannus 
tyrannus) were observed by the writer to capture the moths, and 
others are known to feed freely on moths of this genus. F. M. Web- 
ster states that the wood pewee (Myiochanes virens) was observed to 



14 BULLETIN" 78, U. S. DEPARTMENT OP AGRICULTURE. 

destroy large numbers of Cramhus laqueatellus at Haw Patch, Ind., 
and C. II. Fernald observed barn swallows feeding on different species 
of Cramhus in Maine. Meadowlarks frequent weedy fields which 
harbor the larvae of Crambus, and as these birds are known to feed 
on various species of cutworms, they doubtless feed also on the larvae 
of the tobacco Crambus. 

REPRESSION. 

CULTURAL METHODS OF CONTROL. 

Injury from the tobacco Crambus occurs where crops susceptible 
to injury are grown on weedy land. Tobacco or corn planted on land 
which has been under clean cultivation the previous year and kept 
free from weeds which live throughout the winter does not suffer 
serious injury. The larvse can not live over winter in the soil from 
the previous summer unless plants on which they are able to feed are 
present. All field experiments and observations so far have shown 
that the most effective means of control consist of freeing the land 
from the weeds, such as buckhorn plantain, daisy, stickweed, etc., 
which have been found to be the natural food plants of the larva?. 

There are many methods by which weeds may be eradicated or 
controlled, but the most practical and effective is the systematic 
rotation of crops. Sowing clean seed, preventing weeds from ripen- 
ing seed, fall or winter plowing, the use of lime or of certain fertil- 
izers, and doing away with wide fence rows are important preven- 
tive measures. Mowing and burning over weedy fields destroys 
many weed seeds and weeds which live over winter, and also destroys 
many injurious insects. Burning during August or September has 
been found to destroy the eggs and young larvae of the tobacco 
Crambus, but as this method destroys humus, which is so badly 
needed in most tobacco soils, it is in most instances not advisable. 

Many weeds are "soil indicators/' their presence showing that the 
soil is lacking in fertility and in some instances pointing to a deficiency 
of lime. 

CLEAN SEED. 

One of the main factors in the control of weeds is clean seed, and 
the importance of procuring such seed can hardly be overestimated. 
Many weed pests are introduced and disseminated in the seed of 
various crops, such as grass and clover. As tobacco or corn must 
frequently be grown on land which has previously been in these 
crops, and as injury from the tobacco Crambus is apt to occur if the 
meadows have been weedy, it is desirable, for this and other reasons, 
to have the meadows as free from weeds as possible. 1 Owing to 

1 An analysis made by the Massachusetts Experiment Station shows that 1 ton of oxeye daisy (cured) 
withdraws from the soil approximately 2.5 pounds of potash, 8.7 pounds of phosphoric acid, 22 pounds of 
nitrogen, and 2G pounds of lime. To restore the stated amounts of the first three constituents to the soil 
it would be necessary to apply about 50 pounds of muriate of potash, 65 pounds of superphosphate, and 
140 pounds of nitrate of soda. (Farmers' Bui. 103, V. B. Dept. Agr.) 



THE SO-CALLED TOBACCO WIRE WORM IN VIRGINIA. 15 

careful cultivation of previous crops, the land is frequently fairly 
free from weeds when seeded to meadow; so that if the clover and 
grass seed has been sown pure there will be few weeds in the tobacco 
field or cornfield. 

An examination of samples of clover and grass seed procured 
from farmers and seedsmen in various sections of Virginia shows 
that seeds of buckhorn plantain and oxeye daisy — both natural food 
plants of the tobacco Crambus — are common. Of 30 samples ex- 
amined by the seed expert of the Virginia State department of 
agriculture during 1910, 28 contained seeds of oxeye daisy, and of 
these, 5 contained plantain and daisy. Of 70 samples of clover, 
redtop, and timothy seed examined at the Virginia Experiment 
Station in 1909, seeds of buckhorn plantain were found in 16. 1 

The United States Department of Agriculture and those in charge 
of similar work in many of the States have provided means by which 
samples of seed may be examined for purity by experts. Some of 
the States, also, have laws compelling dealers to furnish a stated 
guaranty as to the purity of the seeds sold. 

WEEDS TO BE ELIMINATED. 

The buckhorn plantain (Plantago lanceolata) is one of the numer- 
ous naturalized weed pests from Europe. It ranks among the worst 
weeds, particularly upon the lighter soils and on clay uplands. 
" Ray-bud," "rib-grass," "ribwort," "buck plantain," "English 
plantain," "ripple," "ripple grass," and "narrow plantain" are 
names applied to the plant in different sections. It is perennial 
or biennial and is common in meadows. The seeds are widely dis- 
tributed with clover seed, from which it is difficult to separate them. 
Rotation of crops, thorough cultivation, and the use of clean farm 
seed are the usual methods for its control. 

The oxeye daisy (Chrysanthemum leucanthemum) (PL II, fig. a) 
is also a naturalized species from Europe. It is often abundant on 
old or poor soil. It spreads from the seeds, which are distributed 
in various farm seeds, in hay, and in manure; also, by shoots from 
the perennial root stocks, which must be entirely killed before the 
plant can be wholly eradicated. It is best controlled by rotation of 
crops, by smothering out by means of cowpeas or other suitable 
soiling crops, and by thorough cultivation. It is a bad weed pest 
in meadowland. The seed can be prevented from ripening by 
mowing the hay early. 

White top or fleabane (Erigeron annuus and other species) is a 
common pest in meadows. In some localities it has been found to 
be a xood plant of the tobacco Crambus. Early mowing of infested 
meadows before the seeds ripen and pasturing with sheep, which 

• Bui. 184, Va. Agr. Exp. Sta. 



16 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

readily eat the weed, are control methods commonly practiced. 
Chemical sprays are fairly effective, but can not be used in meadows 
where clover is grown, as clovers are killed by the solution. Sprays 
have been found most effective while the plant is in bloom. 

The stickweed or aster (Aster ericoides), known also as frost- 
weed, steelweed, white heath, etc., and related species, are com- 
mon and abundant weeds in old fields in tobacco-growing sections 
of the Atlantic States. They are perennial and thrive on poor soil. 
It is useless to try to eradicate them completely, but they can be 
readily controlled by growing cultivated crops and by putting the 
land in a higher state of fertility by the use of lime and clover. 
Aster is not a usual food plant of the tobacco Crambus, but as the 
weed is so frequently associated with daisy and plantain, which 
thrive best under similar soil conditions, its control is essential in 
the preparation of land for tobacco. 

CROP ROTATION. 

One of the main reasons for a rotation of crops is that the accumu- 
lation of weeds in meadowland and pastures may be destroyed 
during the cultivation of the crop that follows. A rotation found 
very satisfactory by the Virginia experiment station has been 
devised by Mr. E. H. Mathewson, Crop Technologist of the Bureau 
of Plant Industry. This plan is slightly modified to meet condi- 
tions in different tobacco-growing sections. It calls for a seven- 
year rotation of crops, as follows: First year, tobacco, fertilized 
heavily; second year, wheat without fertilizing; third and fourth 
years, mixed grasses and clover, seeded alone early in the fall and 
top dressed early in the spring with 200 to 300 pounds of nitrate of 
soda; fifth year, corn, with barnyard manure and a small amount of 
fertilizer; sixth year, cowpeas, fertilized with a Utile acid phosphate 
and sulphate of potash; seventh year, tobacco. 

Crops such as cowpeas, soy beans, and crimson clover, which aid so 
greatly in fitting land for increased and more profitable yields of 
tobacco and corn, not only add humus to the soil and increase the 
fertility, but help to eradicate certain weeds by smothering them out. 
The weeds are also destroyed or prevented from maturing seed when 
crops are plowed under. Although eggs of the Crambus may have 
been deposited in such a field, the larvse can not survive until the 
tobacco is planted unless there are weeds which remain alive over 
winter to supply them with food. 

The following rotation experiments have been under observation 
during the present investigation: 

A test with tobacco following crimson clover was conducted as a 
cooperative experiment on the J. R. Horsley farm in Appomattox 
County, Va., in the season of 1910-11. The field selected contained 



THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 17 

4 acres. It was in corn during the season of 1910. Previous to plow- 
ing for corn the field was in weedy sod. The corn was badly injured 
by the Cranibus and was replanted twice. At the last cultivation of 
corn in July, crimson clover was sown. Rains were frequent during 
the latter part of the summer, and a fairly good stand of clover was 
secured. There were some weeds, in spots, which cultivation at the 
time clover was sown had not destroyed. The field was planted to 
tobacco during the season of 1911. Damage by the Crambus was 
estimated to be about 6 per cent. 

A test with tobacco following cowpeas was conducted as a coop- 
erative experiment on the S. L. Ferguson farm, Appomattox County, 
Va., in the seasons of 1911 and 1912. A field containing about 6 
acres was used in the experiment. The land previous to plowing for 
cowpeas was in weedy pasture, and numerous Crambus larvae had 
been observed. A good growth of the cowpeas was secured. The land 
was deeply plowed during winter and was prepared for planting to 
tobacco during the third week in May, 1912. Scarcely any injury 
from the Crambus to the first planting was observed. After the first 
planting damage from the Crambus and from other causes was esti- 
mated to be less than 4 per cent. In the check field, where conditions 
were similar to those in the experimental field, except that a crop of 
cowpeas had not been grown, there was an estimated damage from 
the Crambus of about 9 per cent. The sod in the check had been 
winter-plowed. 

In the plats of the Virginia Tobacco Experiment Station, at Appo- 
mattox, nine experiments were under observation, as detailed below. 

The first experiment was with tobacco planted on sod in an old 
weedy pasture. A large part of the first planting was destroyed. 
The plat was replanted three times. About 9 per cent of a stand was 
secured by the second week in July. Owing to injury from "wire- 
worms" and' the large percentage of late plants the value of the crop 
was decreased 25 per cent as compared with plats in which an early 
stand of plants had been secured. 

The second experiment was with tobacco following cowpeas on 
land that had been uncultivated for several years and was very weedy. 
Almost a perfect stand of plants was secured at the first planting, 
which was made the last week in May. The injury (decrease in the 
value of the crop) was less than 1 per cent. 

The third experiment was on a plat used for fertilizer tests. The 
conch tion of the land was similar to that used in the second plat, 
except that cowpeas had not been grown during the preceding season. 
The tobacco was replanted three times. The decrease in the value 
of the crop was 7 per cent. 



18 BULLETIN 78, U. S. DEPARTMENT OF AGBTCULTURE. 

The fourth experiment was again with tobacco planted on sod. 
There were few weeds in the sod. Nearly a perfect stand of plants 
was secured at the first planting, which was made during the last 
week in May. The plat was replanted once. The loss was esti- 
mated at less than 1 per cent. 

The fifth experiment was again with tobacco following cowpeas. 
A perfect stand of plants was secured at the first planting, made 
during the last week in May. Injury from the tobacco Crambus was 
estimated at less than 1 per cent. 

The sixth experiment was with tobacco planted on red-clover sod. 
The stand of clover had been good and there were few weeds. To- 
bacco was planted during the last week in May. A good stand was 
secured at the first planting. Loss from the Crambus was estimated 
at less than 1 per cent. 

The seventh experiment was on spring-plowed land where stick- 
weed, daisy, and plantain had been abundant. The tobacco was 
planted during the second and third weeks in May. The loss was 
estimated to be about 20 per cent, owing to late plants, the tobacco 
having been replanted three times. Injury from the Crambus was 
worst in the portion of the field where weeds had been most abundant. 

The eighth experiment was with tobacco following rye. The 
stand of rye had been poor and the stubble was weedy. The first 
planting was made on June 8, and was almost completely destroyed. 
Tobacco was replanted three times. A stand of 90 per cent was 
secured by the second week in July. The estimated decrease in 
the value of the crop was about 30 per cent. 

The ninth experiment was with tobacco fo^owing cowpeas. The 
first planting was made on June 2. About 20 per cent of plants 
were injured by "wireworms." The plat was replanted once, there 
being only slight damage after the second planting. The estimated 
loss in value of the crop was about 10 per cent. Most of the injured 
plants were in the end of the plat where the stand of peas had been 
poor. 

Three experiments were under observation at the Virginia Tobacco 
Experiment Station at Chatham in 1910 by Mr. E. P. Cocke, super- 
intendent of the station. 

In experiment No. 1 tobacco was preceded by corn in which 
crimson clover was sown at the last cultivation. This clover was 
fallowed May 2. The corn was kept clean of weeds and grass. 
Tobacco was set June 6. The first replanting was made June 14 
with 5 per cent of the plants injured; the second replanting was 
made June 28, w T ith 3 per cent injury; and the third replanting, 
June 28, with 2 per cent injury. About 97 per cent of a stand was 
finally secured after the third replanting. 



THE SO-CALLED TOBACCO WTREWORJM IX VIRGINIA. 19 

In experiment No. 2 tobacco followed corn, in a plat used for 
fertilizer tests. Tobacco was set June 6. The first replanting was 
made June 14, with 5 per. cent injury; the second replanting, June 
23, with 3 per cent injury; and the third replanting, June 28, with 
2 per cent injury. About 98 per cent of a stand was secured after 
the third replanting. 

In experiment No. 3 tobacco was planted after a cover crop of 
wheat, hi variety test plats. The wheat was fallowed May 1 . Tobacco 
was set June 7. The first replanting was made June 17, with 20 per 
cent injury, and the second replanting, June 28, with 6 per cent 
injury. About 95 per cent of a stand was secured. In these plats 
it was estimated that about 5 per cent of the entire loss was due to 
cutworms and to true wireworms (larva? of Elaterida?) . 

SUMMER PLOWING. 

The moths are local in habits and do not fly far from the weedy 
fields, which furnish protection for them and which are suitable 
places for them in which to deposit eggs. On emerging from plowed 
or bare land, or from fields in which the vegetation is not suitable 
for protection or for egg deposition, they fly to surrounding fields 
where conditions are more favorable. The land from which emer- 
gence took place will then be left free from worms which, if present 
would attack the crop the following year. 

The preparation of weedy land for tobacco or corn must, therefore, 
be commenced the season before the crop is planted. Best results have 
been obtained by summer plowing, as the land was thus rendered 
bare of vegetation, and conditions were not suitable for egg laying 
when the moths emerged. By this means infestation of the land is 
prevented in the first place. It has been found that it is difficult 
to prevent injury, or to eradicate the worms, if they have once 
become established. Summer treatment of land makes conditions 
unfavorable for the moths to deposit eggs, destroys weeds which 
furnish food for the young larva?, and kills many of the insects while 
in the pupal stage. 

The results of an experiment made in 1910 to ascertain the effect 
of plowing on pupa? is given in Table VIII. Larva? were placed in 
large field cages. When the greater number had pupated, one of 
the cages was removed temporarily and the land plowed. 

Table VIII. — Effect of plowing on pupal stage of the. tobacco Crambus. 



Cage No. 


Number 
of larvae. 


Collected. Moths emerged. ^™~ f £™ 


1 


200 
200 


June: Second and third week.. . Julv: Third and fourth week. . 84 42 


2 (check)... 


do I do lis 59 



20 BULLETIN 78, IT. B. DEPARTMENT OF AGRICULTURE. 

Pupation takes place at an average depth of 1£ inches. The pupal 
cells are fragile and easily broken up by plowing or disking. Many 
of the pupae are deeply buried by plowing and the moths are unable 
to reach the surface. 

The satisfactory results following summer treatment of land, 
whether or not cowpeas or other similar crops are grown, are mainly 
due to the fact that conditions are made unfavorable for the deposi- 
tion of eggs by the moths and for the growth of newly hatched larvae. 

FALL AND WINTER TREATMENT OF LAND. 

During September, 1909, two cultural experiments were begun in 
Appomattox, Va., to ascertain the effect of fall and winder treatment 
of land already infested with Crambus larvae. 

The field selected on the J. F. Purdum farm contained five plats 
of one-half acre each. In this experiment (experiment A) fall and 
winter preparation of the tobacco land gave decidedly beneficial 
results. The field had been in pasture previous to plowing, but the 
growth of weeds was not so rank as on the land used in experiment B. 
The following were the results obtained in each of the plats: 

Plat No. 1. — Ground plowed during second week in December, 1909. Thoroughly 
disked during first week in January, 1910. Tobacco planted during last week in May. 
Number of plants, 2,200. Number replanted, 89. Per cent injured, 4+. 

Plat No. 2.— Land plowed during first week in January, 1910. Disked during 
second week in February. Tobacco planted during last week in May. Number of 
plants, 2,350. Number of plants reset, 165. Per cent injured, 7+. 

Plat No. 3. — Land plowed during last week in February, 1910. Disked during third 
week in March. Tobacco planted during last week in May. Number of plants, 2,280. 
Number of plants reset, 138. Per cent injured, 6+. 

Plat No. 4- — Land plowed during third week in March, 1910. Disked during third 
week in April. Tobacco planted during last week in May. Number of plants, 2,214. 
Number of plants reset, 251. Per cent injured, 11 + . 

Plat No. .5 {check plat). — Land plowed during third week in April. Prepared for 
planting during last week in May. Tobacco planted during last week in May. Num- 
ber of plants, 2,225. Number reset, 375. Per cent injured, 17 + . 

Tobacco in all plats was replanted twice. A good stand of plants 
(about 98 per cent) was secured by July 4. After July 4 there was 
but slight injury from the worms. The land had been heavily 
fertilized, and the tobacco made a fine growth. 

The second tobacco cultural experiment was conducted on the farm 
of Mr. J. R. Horsley (experiment B), in Appomattox County, Va. 
Four plats, each containing 1 acre, were included in the experiment. 
Two check plats, one at each end of the experimental plats, were 
used. Each of these contained 1 acre. The growth of weeds was 
heavy, stickweed, daisy, and buckhorn plantain being abundant. 

\\i this test beneficial results from fall and winter plowing were not 
so conclusive as in the experiment on the Purdum farm (experiment 



THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 



21 



A). On plat No. 1 the effect of mowing and burning the weeds after 
the eggs had hatched was noted. 

Plat No. 1. — Weeds mowed and burned during third week in September, 1909. 
The land was not disturbed until the ground was prepared for planting, during the 
third week in May. Number of plants in plat, 4,400. Number of plants reset, 610. 
Per cent injured, 13. 8+. Tobacco replanted twice. 

Plat No. 2. — Ground plowed during last week in September, 1909. In March, 
April, and May it was disked and harrowed at frequent intervals, no vegetation being 
allowed to grow before the tobacco was planted, in order, if possible, to starve out the 
hibernating larvse. Number of plants, 4,400. Number replanted, 415. Per cent 
injured, 9.44-. 

Plat No. 3. — Land plowed during second week in March and not disturbed until 
just before planting. Number of plants, 4.400. Number of plants reset, 410. Per 
cent injured, 9.3-4-. 

Plat No. 4. — Land plowed during third week in December, 1909. Nothing further 
done to it until prepared for planting during last week in May, 1910. Number of 
plants, 4,400. Number replanted, 540. Per cent injured, 12. 2+. 

The results of these experiments are shown also in Table IX. 
All plats were replanted twice. A good stand of 98 per cent was 
secured by July 5. 



Table IX.- 



-Effects of fall and winter treatment on injury by the tobacco Crambus 
in 1909 and 1910. 



Exper- 
iment 
No. 



A2 

A3 

A4 

A 5 
Bl 

B2 
B3 
B4 
B5 



Preliminary treat- 
ment. 



Time of treatment. 



Plowed 

....do 

do 

do 

....do 

Weeds mowed and 
burned. 

Plowed 

....do 

....do 



Second week of December, 1909. 

First week of January, 1910 

Last week of February 

Third week of March ' 



Third week of April 

Third week of September, 1909. 



Later treatment. 



Thoroughly disked. 

Disked 

do 

do 



Disked and har- 
Last week of September j. rowed at f re- 
Second week of March quent intervals. 

Third week of December j 

First week of April Disked 



First week of 

January, 

1910. 
Second week of 

February. 
Third wee'k of 

March. 
Third week of 

April. 



March, April, 
May. 

First week of 
May. 



Exper- 
iment 
No. 


Planted tobacco. 


Number 
ofplants. 


Number 
reset. 


Per cent 
injury. , 


Al 




2,200 
2, 350 
2,280 
2,214 
2, 225 
4,400 
4,400 
4,400 
4,400 
8,800 


89 
165 
138 
251 
375 
610 
415 
410 
540 
1,218 


4 


A2 


do 




A3 


do 


6 


A4 


do 


11 


A5 


do :. 


17 


Bl 




13.8 


B2 


do 


9.4 


B3 


do 


9.3 


B4 


do 


12.2 


Bo 


do 


13.9 









In the season of 1910-11 another series of cultural experiments was 
conducted on the J. F. Purdum farm, in Appomattox County, Va 
The land previous to preparation for tobacco was in meadow 



22 BULLETIN 78, l". S. DEPARTMENT OF AGRICULTURE. 

(timothy, herd's grass, and clovei) which had been quite weedy. 
Natural food plants of the tobacco Crambus were abundant. This 
series was made for the purpose of ascertaining the effect on the 
tobacco Crambus of preparation of weedy land at different times 
during the fall and winter as compared -with spring preparation of 
land. The field was divided into 6 plats containing one-half acre 
each. Tobacco was planted in all plats on the same date. The 
amount of fertilizer applied to each plat was the same. 

In plat Xo. 1 the land was plowed September 6, 1910, and fallowed 
February 25, 1911. It was harrowed and disked on April 3, April 10, 
April 20, and May 3. The stand of tobacco was nearly perfect after 
the first planting except along one end of the plat. The percentage 
of a stand secured was 95.4. In the preparation of this plat it will be 
nfrticed that the land was plowed during the first part of September, 
a time just after the larvae had hatched. 

Plat No. 2 was plowed December 8, 1910, and fallowed February 28, 
1911. It was harrowed and disked on April 3, April 10, April 20, and 
May 3. Tobacco was replanted once. About 85 per cent of a stand 
was secured at the first planting. 

Plat No. 3 was plowed January 8, 1911, and fallowed or replowed 
February 28, 1911. It was harrowed and disked on April 3, 10, and 20 
and May 3. Tobacco was replanted once. About 85 per cent of a 
stand was secured at the first planting. 

In plat No. 4 the land was plowed on April 11. No further treat- 
ment was given until the third week in May, when the land was 
prepared and bedded for planting. The tobacco was replanted three 
times. About 51 per cent of a stand was secured at the first planting. 

In plat No. 5 the land was plowed on January 18, 1911, and disked 
May 15. Tobacco was replanted three times. About 70 per cent 
of a stand w r as secured at the first planting. 

Plat No. 6 served as a check plat. The land was plowed during 
the third week in April, and was prepared for planting on May 15. 
Tobacco was replanted three times. About 55 per cent of a stand was 
secured after the first planting. 

Further cultural experiments were conducted on the S. L. Ferguson 
farm, in Appomattox County, Va., in the season of 1911-12. This 
series was made to ascertain the effect of deep winter plowing and 
subsoiling of pasture Jand infested by the Crambus. The field of 
which the experimental plats were a part had been in sod for a number 
of years and was used as pasture land. The general conditions for 
the experiment were ideal. The oxeye daisy, buckhorn plantain, 
and stickweed were abundant. There was not a rank growth of 
weeds, however, as the field had been quite closely pastured. The 
field was deeply plowed in February, a subsoil plow following the 
turning plow, and 1 he clay subsoil was broken up to a depth of several 



THE SO-CALLED TOBACCO WIREWORM IN VIRGINIA. 23 

inches. The tobacco in all plats was planted at the same time. The 
kind and amount of fertilizer applied was the same in all plats, and 
after the first cultivation all plats received the same treatment. The 
land was divided into 3 plats of 2 acres each and 1 plat containing 
one-half acre. Below are given the details of each experiment and 
the results obtained. 

Plat No. 1 contained 2 acres. It was deeply plowed and subsoiled 
in February, 1911 . The land was thoroughly disked and harrowed at 
frequent intervals during March, April, and May and kept almost 
entirely free from weed growth until tobacco was planted. The stand 
of tobacco was practically perfect. Only an occasional plat could be 
found which showed damage from Crambus larvae. 

Plat No. 2 contained 2 acres. The land was deeply plowed and 
subsoiled in February, 1911, and was not disturbed until prepared for 
planting in May, when it was deeply disked, harrowed, and bedded 
just before planting. Ninety-four per cent of a stand was secured at 
the first planting. The plat was reset once. 

Plat No. 3 contained one-half acre. The land was plowed and sub- 
soiled in February, 1911, as in plats Nos. 1 and 2. The land was not 
disturbed until prepared for planting as in plat No. 2. Weeds and 
grass were allowed to grow after planting. The middle of the row 
was not disturbed until after the first cultivation, in order to provide 
natural food for the Crambus larvae, so that they would not be forced 
to attack the tobacco plants. The infestation of this plat was not 
heavy enough, so that the effect of tins treatment, which is said to be 
practicable under certain conditions, could be accurately determined. 
The stand of tobacco secured at the first planting was 96 per cent. A 
few larvae were found in the weeds left in the middle of the row. 

Plat No. 4 was used as a check. The land was plowed and pre- 
pared for planting just before the tobacco was set out. The w^eed 
growth and general conditions were similar to those in plats Nos. 1, 
2, and 3. The stand secured at first planting was 86 per cent. The 
tobacco was replanted twice. In land adjoining this tract which had 
been under clean cultivation during the previous summer and where 
there was no weed growth, about 98 per cent of a stand of tobacco 
was secured at the first planting. This land had been prepared for 
planting in practically the same manner as in the check plat, No. 4. 

CHEMICAL SPRAYS FOR WEED DESTRUCTION. 

Certain chemical sprays, such as iron-sulphate (copperas) solution, 
copper-sulphate (bluestone) solution, and common-salt solution, are 
frequently used for eradicating weeds and under certain conditions 
have been found very effective. The success of this method of erad- 
icating such weeds as oxeye daisy and wild mustard from grain and 
pasture fields without injury to the grains or grasses depends largely 



24 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

on the fact that cereals and grasses are narrow-leaved plants with a 
single seed leaf, whereas the weeds injured are broad-leaved plants 
with two seed leaves. Spraying with a solution of iron sulphate at a 
strength of 1 pound to one-half gallon of water was found to be fairly 
effective on the oxeye daisy in a test made at Appomattox, Va. 
While spraying may be practical where certain weeds in grain fields 
are to be eradicated, it is hardly a suitable remedy under most con- 
ditions in tobacco-growing sections, except possibly where small, 
patches of weeds are to be destroyed. Chemical sprays have been 
found to be more effective when applied on warm bright days when 
the plants are dry. Immediately after weeds have been cut off close 
to the ground an application of salt, kerosene, crude oil, or acid 
solutions will often be found effective. In eradicating weeds from 
pastures the salt solution is preferable, as copper-sulphate solution is 
poisonous to stock. 

LIMING. 

Aside from improving the mechanical and chemical condition of 
many soils, liming will be found to aid greatly in the control of several 
of the weed pests which have been found to be the natural or favorite 
food plants of the tobacco Crambus. Control of weed pests may be 
accomplished by making soil conditions less favorable for the weeds, or 
by making conditions more favorable to the cultivated crop. Many 
weed pests, like other plants, require for their best development certain 
soil conditions ; and they are excessively abundant in certain locali- 
ties because soil conditions are peculiarly favorable to their growth, 
or because conditions are less suited to more desirable plants which 
under favorable soil conditions would crowd them out. A change in 
the condition of the soil, brought about by the use of lime, will often 
bring about a marked effect in checking or preventing the growth of 
a weed pest, and at the same time make the soil better adapted to the 
growth of certain cultivated crops such as clover. 

The sheep sorrel ' (Rumex acetosella), on which newly hatched 
Crambus larvae- frequently feed, thrives in acid soil. Where lime had 
been applied to certain fields, and to some of the State experiment 
station plats in Appomattox County, Va., the sheep sorrel was 
practically eradicated or at least checked by the better growth of the 
clover. Plantain, daisy, and aster (stickweed), all food plants of 
the worms, are weeds which flourish in acid or worn-out soils. In all 
cases where data have been secured, the use of lime has resulted in a 
marked decrease in the abundance of these weeds. Most soils in the 
Piedmont region of the Eastern States are greatly benefited by lime, 
and its use has in many instances resulted in markedly increased yields 
of tobacco. In plats of alfalfa at the Appomattox experiment station 

1 Attempts to rear larvae in cages containing only sheep sorrel were not successful. 



THE SO-CALLED TOBACCO WIRE WORM IN VIRGINIA. 25 

there was scarcely any plantain (Plantago lanceolata) after a heavy 
application of lime had been made, and there was an excellent crop 
of alfalfa. In the unlimed check plats plantain nearly covered the 
ground, and there was a very poor growth of alfalfa. 

Increased fertility of the soil may also aid in the extermination of a 
weed, as was noticed where heavy applications of acid phosphate had 
been made to meadow land on which there was a heavy growth of 
the oxeye daisy. The year following the application of the acid 
phosphate but few plants of the daisy could be seen. In this manner 
certain weeds may often be crowded out by grasses or clovers which 
are enabled to make better growth owing to greater fertility. 

The experience of the best tobacco growers has shown that intensive 
culture gives largest profits, and no expense or trouble should be 
spared in putting the ground in the best possible condition in every 
respect before the crop is planted. By commencing the preparation 
of weedy land the year before it comes in corn or tobacco, an excellent 
opportunity is afforded to apply lime. Such land can often be con- 
veniently plowed in winter and during spring or early summer, and 
easily be put in condition for such crops as crimson clover, cowpeas, 
etc., which may be profitably followed by tobacco or corn the succeed- 
ing year. 

FERTILIZERS. 

From observations of tobacco fields during the seasons of 1910 
and 1911 it is evident that where the land receives heavy applications 
of nitrogenous fertilizers the damage from the worms is not so great 
as where light applications are made. Just as many plants are 
attacked by the worms, but vigorous and rapidly growing plants 
are more apt to recover from injury. This was very noticeable in the 
fertilizer test plats of the Virginia experiment station at Appomattox 
in 1910. 

INSECTICIDES AND REPELLENTS. 

The following insecticides and repellents were tested: Arsenate of 
lead, Paris green, tobacco extract, nicotine sulphate, tobacco dust, 
kerosene, kainit, and calcium cyanamid. In no instance were results 
secured which would indicate that the substances tested were of much 
practical value in combating the tobacco Crambus. The following 
field notes give details of some of the experiments : 

ARSENATE OF LEAD. 

In experiment A, with powdered arsenate of lead, 1^ ounces of the poison to 2 \ 
gallons of water was used. Two hundred plants were treated, the entire plant being 
dipped into the solution. The plants were set in land which had been prepared a 
few days before. The field had been weedy and the worms were numerous. Two 
hundred untreated plants were kept as a check. On examining the plants five days 
later 22 injured plants were found in the poisoned plat and 36 injured plants in the 



26 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

check plat. Three live larva; which had tunnelled in the stalks and were apparently 
uninjured were found in plants in the poisoned plat. All treated plants had lived, 
but were not as vigorous in appearance as those not treated. 

In experiment B, with arsenate of lead paste, the poison was used at the rate of 
2 ounces to 2\ gallons of water. The tops only were dipped. One hundred plants 
were treated and 100 left untreated. The plants were examined five days after trans- 
planting. There had apparently been some injury from the poison, as the plants 
were in best condition in the untreated plat, while those treated were somewhat 
stunted or dwarfed. Eight injured plants were found in the poisoned plat. Five 
plants were found injured in the untreated plat. 

PARIS GREEN. 

Paris green at the rate of one-fourth ounce to 3 gallons of water was used on 100 
tobacco plants, and an adjoining row kept as a check. The entire plant was dipped 
in each case, and the plants set out at once. The field was weedy. It had been 
recently plowed and Crambus larvee were numerous. A light rain fell a few hours 
after the plants were set. After eight days the plants were examined. Twenty-one 
plants were injured by worms in the poisoned row and 26 in the unpoisoned row. 
There had been some injury to the plants dipped in the poison solution, as the un- 
poisoned plants had a more vigorous start. In some instances plants in the poisoned 
row were only slightly eaten, thus indicating that the poison had acted as a repellent 
or had poisoned the worm before the plant had been badly eaten. 

TOBACCO EXTRACT. 

One row of tobacco plants in a field was sprayed with a 500-to-l solution of tobacco 
extract, 320 plants in all being treated. The solution was applied with a compressed- 
air bucket sprayer. The substance did not prove effective in preventing injury. 
On June 6, five days after the mixture was applied, the plants were examined. 
Fourteen plants were found injured by worms in the sprayed row and 11 injured 
plants were found in the unsprayed row adjoining. 

NICOTINE SULPHATE. 

A 1,000-to-l solution of nicotine sulphate was sprayed on 300 plants as in the fore- 
going experiment, and an adjoining row used as a check. The plants were examined 
four days after spraying. Eight plants had been attacked by worms in the sprayed 
row and 13 plants in the check row. While the foregoing substances did not prove of 
much value in' preventing injury from the worms, they seemed to repel flea-beetles, 
as very few could be found on the treated plants whereas they were comparatively 
abundant on the unsprayed plants. 

TOBACCO DUST. 

Tobacco dust was scattered about tobacco plants directly after planting. One row 
containing 300 plants was used for the test and an adjoining row with the same number 
as a check. Eighteen plants were found injured by worms in the treated row. Few 
plants were found that were injured below the surface of the ground, the worm having 
entered the plant at the "bud " or terminal leaf in most cases. Sixteen injured plants 
were found in the row where the dust had not been applied. More of these plants 
had been injured below the surface of tlie soil than where dust had been applied, this 
indicating that the dust may possibly have some value as a repellent. 

KEROSENE. 

In the first experiment with kerosene the plants were dipped in a weak solution 
of kerosene emulsion and were set out on June 15. Only 30 plants were used in the 
test. None of these, when examined five days later, was found infested. There was 
apparently no injury to the plants from the kerosene. Two infested plants were 



THE SO-CALLED TOBACCO WIREWOEM IN VIRGINIA. 27 

found in the check row of 30 plants. The number .of plants treated was not large 
enough to make this test of much value. 

In the second experiment kerosene was mixed with sand and a small amount 
sprinkled around 100 tobacco plants. One hundred plants in an adjoining row were 
used as a check. A light rain fell a few hours after the sand was applied. On June 
18, eight days after treatment, the plants were examined. Sixteen were found 
injured in the treated row and 22 in the untreated row. 

KAINIT. 

In one experiment kainit was mixed with the soil in the hill before planting. Too 
large a quantity of the kainit was used in the test, as a considerable number of plants 
failed to grow. One hundred tobacco plants were put out in soil mixed with the 
kainit, and 100 plants in an adjoining row were left for a check. A number of infested 
plants were found where the kainit had been used, the substance evidently not being 
of much value as a preventive, as the worms often enter the plant at the "bud" or 
whorl of terminal leaves. 

TURPENTINE. 

In certain sections of Tennessee and Kentucky turpentine is said to have been used 
as a repellent for Crambus larvae and cutworms. Before planting, the roots of the 
tobacco plants are dipped in water in which a small quantity of turpentine has been 
stirred . 

A test on 1 acre of tobacco was made by Mr. Charles Armistead, of Clarksville, Tenn., 
and the field kept under observation by the writer. Entirely negative results were 
obtained. The following are details of the experiment: The tobacco was on weedy 
land containing an abundance of white top (Erigeron annum) and plantain. The 
first planting was entirely destroyed. When the tobacco was replanted turpentine 
was used at the rate of 1 teaspoonful to 1 gallon of water, the roots of the plants being- 
dipped in the mixture. On June 27, two weeks after planting, the tobacco was 
examined. Worms were still very numerous. Over 80 per cent of the plants had 
been entirely destroyed, in both treated and check plats. There seemed no apparent 
difference in infestation and damage between the treated tobacco and that on which 
no turpentine had been applied. 

CALCIUM CYANAMID. 

Calcium cyanamid (lime nitrogen) is said to have a repellent or poisonous effect 
upon insects, and on the suggestion of Mr. E. H. Mathewson, Crop Technologist of the 
Bureau of Plant Industry, Mr. B. G. Anderson, superintendent of the Tobacco Experi- 
ment Station at Appomattox, Va., and the writer made a test of the material during 
1 911, using the calcium cyanamid at the rate of 300 pounds per acre. The land selected 
had not been cultivated for several years. There was a rank growth of buckhorn 
plantain, oxeye daisy, and stickweed, and Crambus larvae were exceedingly numer- 
ous, making conditions ideal for the test. The plat, containing one-twentieth of an 
acre, was divided into series of two rows each. The calcium cyanamid was used on 
two rows and the next two rows were kept as a check. On the treated rows com- 
mercial fertilizer at the following rate per acre was used : 

Pounds. 

Calcium cyanamid 300 

Acid phosphate , 600 

Sulphate of potash 100 

On the check rows the fertilizer used (rate per acre) was as follows: 

Pounds. 

16 per cent blood 300 

Acid phosphate 600 

Sulphate of potash , 100 



28 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

The calcium cyanamid analyzed about 17 per cent ammonia, this making the 
amount of plant food in the treated and check rows practically the same. The fer- 
tilizer was applied 14 days before the plants were set, as calcium cyanamid has the 
effect of stunting tobacco plants if applied directly before planting. It was applied 
to the mws with a. drill, and thoroughly mixed with the soil by running a cultivator 
over the rows. The plants were set on June 8. By June 30 the plants in both treated 
and check rows had been almost completely destroyed by the Crambus larva?, there 
being no indications of any beneficial effect from the calcium cyanamid in preventing 
injury. The tobacco was not replanted. 

LEAD ARSENATE AND PARIS GREEN USED WITH COAL TAR ON SEED CORN TO PREVENT 
INJURY BY CRAMBUS LARV.E. 

Experiments in the use of arsenate of lead and Paris green with coal tar on seed 
coin to prevent injury by Crambus larvae were conducted in 1910 on the J. F. Pur- 
' dum farm. 

In experiment A, arsenate of lead in paste form was used at the rate of 1 ounce to 
1 gallon of water. One peck of shelled seed corn was allowed to soak in the solution 
about 10 minutes and dried by mixing with fertilizer (acid phosphate). A very little 
coal tar (about a tablespoonful) was then poured on the corn, which was thoroughly 
stirred until a thin coating of the tar covered each kernel. Fertilizer was then used to 
dry the tar. With an ordinary planter one-half acre was planted in seed prepared as 
just described. Fully one-third of the corn failed to germinate, possibly owing to 
exclusion of moisture from the seed by the tar, as the weather was dry. No benefit 
in preventing injury by the worms seemed to result. In the check plat the stand 
of corn was practically perfect. On June 16, four weeks after planting, a count was 
made in the treated and check plats of hills of corn showing Crambus injury. Eleven 
per cent of the hills showed injury in the treated plat and 13 per cent in the check 
plat. 

In experiment B, 1 ounce of Paris green was used to 1 peck of shelled seed corn. 
A small amount of tar (about one tablespoonful) was poured over the corn, which 
was thoroughly stirred until a thin coating of tar covered each kernel. The corn 
was then dried by mixing with fertilizer to which Paris green had been added. One- 
half acre was planted with seed prepared in this manner. About one-fifth of the 
seed failed to grow. In the check plat the stand was practically perfect. 

A count of hills of corn showing Crambus injury, made on June 16, four weeks 
after planting, showed the results of the treatment to be as follows: Injury in treated 
plat, 11 per cent; injury in check plat, 9.5 per cent. 

SUMMARY OF ECONOMIC CONTROL. 

(1) The eggs of the tobacco Crambus are deposited in weedy fields 
during July and August. They hatch in a few days. The larvae 

i remain over winter in the soil and complete their growth during 
June and July. They are in their most active feeding stage at the 
time tobacco or corn is planted. 

(2) Injury to tobacco or corn occurs when these crops are planted 
on land which was weedy during the previous year. Crops planted 
on land which has been under clean cultivation are immune from 
injury. 

(3) The weeds which have been found to be the more common 
natural food plants of the worms are the buckhorn plantain, oxeye 
daisy, stickweed, and whitetop. The presence of these weeds in 
meadows accounts for injury to tobacco or corn when planted on sod. 



THE SO-CALLED TOBACCO WIRE WORM IN VIRGINIA. 29 

(4) The worms when once established in land where their natural 
food plants are abundant have been found difficult to control. 

(5) Various insecticides and repellents have been tested, but 
without satisfactory results. 

(6) Fall or winter plowing has been found to reduce injury, but 
is only partially effective, as some of the weeds remain alive and 
furnish food for the larvae until the tobacco or corn is planted. 

(7) Damage is best prevented by crop rotations, or by cultural 
methods that prevent growth of the weeds which are food plants of 
the worms, thus making conditions unfavorable for egg deposition by 
the moths the summer before tobacco or corn is planted. Summer 
plowing, thorough preparation of weedy land, and the growing of 
crops of cowpeas or crimson clover, preferably cowpeas, the year 
before crops subject to injury are planted, have been found to be the 
most satisfactory and practical means of control. 

BIBLIOGRAPHY. 

1860. Clemens, Brackenridge. Contributions to American lepidopterology. No. 
5. Proc. Acad. Nat, Sci. Phila. for 1860, p. 203-221, June, 1860. 
The original description of Crambus caliginosellus, p. 204. 

1880. Grote, A. R. Preliminary list of North American species of Crambus. Canada 
Ent., v. 12, no. 4, p. 77-80, Apr., 1880. 
Gives habitat, N. Y., p. 79. 

1887. Moffat, J. A. Further additions to the list of Canadian microlepidoptera. 
Canad. Ent., v. 19, no. 5, p. 88-89, May, 1887. 

Specimen of Crambus caliginosellus in collection of Mr. Moffat, Hamilton, Ont., deter- 
mined by Fernald. 

1891. Beckwith, M. H. Notes on a corn crambid. U. S. Dept. Agr., Div. Ent., 
Insect Life, v. 4, no. 1-2, p. 42^3, Oct., 1891. 

Brief mention. Dr. J. B. Smith reports insect as injuring corn in New Jersey. Dr. L. O. 
Howard reports insect as abundant in Maryland in 18S6. 

1891. Beckwith, M. H. Notes on a corn crambid. Del. Col. Agr. Exp. Sta,, Bui. 
14, p. 13-15, fig. 1, Dec, 1891. 

Mention of species as injurious to corn in Delaware. Account of feeding habit of larvae. 
1894. Felt, E. P. On certain grass-eating insects. Cornell Univ. Agr. Exp. Sta., 
Bui. 64, p. 47-102, 14 pis., Mar., 1894. 

"The sooty crambus," p. 61-62. Brief account of moth; description of eggs and newly 
hatched larvae. 

1896. Fernald, C. H. The Crambidas of North America. Mass. Agr. Col. Ann. 

Rpt. 33 (Pub. Doc. 31), p. 77-165, pis. 6 & A-B, Jan., 1896. 
Redescription of moth, p. 137-138. 

1897. Johnson, W. G. Notes on some little-known insects of economic importance. 

U. S. Dept. Agr., Div. Ent,, Bui., n. s., no. 9, p. 83-85, 1897. 
"Crambus caliginosellus," p. 84. Account of injury to corn in Maryland. 

1898. Johnson, W. G. Report on the San Jose scale in Maryland and remedies for 

its suppression and control. Md. Agr. Exp. Sta., Bui. 57, 116 p., 26 figs., 
Aug., 1898. 

" Crambus calignosellus," p. 9. Account of injury and feeding habits of larvae. 

1898. Johnson, W. G. Notes from Maryland on the principal injurious insects of 

the year. U. S. Dept, Agr., Div. Ent., Bui., n. s., no. 17. p. 92-94, 1898. 

"The corn crambus," p. 93. Brief mention as destructive in various parts of the State- 



30 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 

1899. Johnson, W. G. The stalk worm: A new enemy to young tobacco. U. S. 

Dept. Agr., Div. Ent., Bui., n. s., no. 20, p. 99-102, 1899. 

An account of injury to tobacco by C. caliginosellus. States that tobacco growers in 
southern Maryland reported injury for last fifteen years, or possibly longer. Recommends 
system of crop rotation aimed at control. 

1900. Johnson, W. G. Notes on insects of economic importance for 1900. U. S. 

Dept. Agr., Div. Ent., Bui., n. s., no. 26, p. 80-84, 1900. 

Brief mention of Crambus caliginosellus. Reports insect as destructive to tobacco on 
sod lands, p. S3. 

1902. Sanderson, E. D. Insects injurious to staple crops. New York, 1902. 

"The corn-root webworm (Crambus caliginosellus Clem.)," p. 130-134. Account of 
injury to corn and tobacco. Recommendations concerning control. 

1903. Chittenden, F. H. The principal injurious insects in 1902. U. S. Dept. 

Agr. Yearbook for 1902, p. 726-733, 1903. 

Brief mention of Crambus caliginosellus. One of the most destructive insects to corn in 
Delaware in 1902, p. 729. 

1907. McNess, G. T., Mathewson, E. H., and Anderson, B. G. The improvement 
of fire-cured tobacco. Va. Agr. Exp. Sta., Bui. 166, p. 186-234, May, 1907. 
Account of difficulty of securing a satisfactory stand of tobacco in experimental work; 
description of injury to plants. 

1909. Mathewson, E. H. Intensive methods and systematic rotation of crops in 
tobacco culture. U. S. Dept. Agr. Yearbook for 1908, p. 403-420, pi. 33-37, 
1909. 

Mention of tobacco "wireworm" or "stalkworm" and effect of crop rotation on control. 
p. 411. 

1911. Runner, G. A. Report upon tobacco insect investigations. Va. Polytech 
Inst. Agr. Exp. Sta., Ann. Rpt. for 1909 and 1910, p. 40-43, 1911. 

Amount of economic importance of insect, food plants, feeding habits of larvae. Recom 
mendations concerning control, p. 41-42. 

1911. Morgan, A. C. Insect enemies of tobacco in the United States. U. S. Dept. 

Agr. Yearbook for 1910, p. 281-296. 
Brief mention of tobacco Crambus, p. 291. 

1912. Hunter, W. D. Relation between rotation systems and insect injury in the 

South. TJ. S. Dept, Agr. Yearbook for 1911, p. 201-210, 1912. 
Discussion of importance of systems of crop rotation in relation to control. 

o 

WASHINGTON : GOVERNMENT PRINTING OFFICE: 1914 




BULLETIN OF THE 

UMffiOTOFAfflCDUl! 



No.79 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief 
April 23, 1914. 

(PROFESSIONAL PAPER.) 




RESEARCH STUDIES ON THE CURING OF LEAF 

TOBACCO. 

By W. W. Garner, Physiologist in Charge, C. W. Bacon, Assistcmt Physiologist, and 
C. L. Fotjbert, Assistant in Tobacco Chemistry, Tobacco and Plant-Nutrition 
Investigations. 

INTRODUCTION. 

The term " curing," as applied to tobacco, is somewhat indefinite 
in meaning, being used sometimes to include the separate operations 
of barn curing, fermentation, and aging, or afterfermentation, while 
the farmer usually restricts the term to the process of drying the ripe 
leaf in a specially constructed barn and under such conditions as 
will develop the desired properties or qualities. In the present 
article the term is used in the last-named more restricted sense, so 
that we have only to consider curing as far as it proceeds in the 
curing barn. 

The methods now in vogue in barn curing are almost entirely 
empirical, being the result of practical experience extending through 
several generations, and in general are based more or less on rule-of- 
thumb procedures, without sufficient flexibility to meet changing 
conditions and requirements. The barn curing of tobacco has not 
received the attention from investigators that has been given the 
subsequent process of fermentation, and such investigations as have 
been made relate mostly to certain special phases of the subject. 

There are two general methods of harvesting tobacco and arranging 
it in the barn which materially affect the results obtained in curing. 1 
In the one case the leaves are picked from the stalk as they mature 
or "ripen" and are arranged on strings or sticks suitable for hanging 
in the curing shed, this method being popularly spoken of as priming. 
In the other method the leaves are not removed from the stalks, but 
the latter are cut off near the ground and suspended in an inverted 

1 For details of these methods consult Garner, W. Y\"., Principles and practical methods of curing tobacco, 
U. S. Department of Agriculture, Bureau of Plant Industry, Bulletin 143, 54 p., 10 fig., 1909. 

Note. — This bulletin gives the results of a study of the physiological changes occurring in curing 
tobacco In the barn and is of special interest to those concerned with the improvement of tobacco curing. 

29731°— 14 1 



2 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 

manner in the barn. There is an important modification of the 
method of harvesting and curing the leaves on the stalk in that, 
prior to being severed near the base, the stalk is split longitudinally 
from the top down the greater part of its length and when cut is 
placed astride a stick for hanging in the barn. 

NATURE OF THE CURING PROCESS. 

Observant growers well know that tobacco leaves which have been 
killed by freezing or by bruising do not cure normally, and a leaf 
which is quickly dried by heat does not possess the properties of 
the cured leaf. Moreover, if the fresh leaf is subjected for a few 
minutes to the action of protoplasmic poisons, such as formaldehyde 
or chloroform, it will not cure properly. It is quite evident, therefore, 
that curing is a life process and thus differs fundamentally from the 
subsequent fermentation, which takes place after the death of the 
leaf cells. That curing is essentially a life process can also be readily 
shown by chemical analysis, as is brought out in later paragraphs. 

Curing materially changes the physical and chemical properties 
of the tobacco leaf, more particularly such properties or qualities 
as the capacity to hold fire, the color, the texture, and the elasticity. 
It does not develop the aroma, however. With respect to the 
development of some of the above-mentioned properties of the leaf, 
fermentation may be regarded as supplementary to curing; but, as we 
hope to show more fully in a later publication, some of the important 
changes in composition involved in curing are not continued in the 
fermentation, so that incomplete curing can not be fully corrected 
in the subsequent fermentation. 

As will be shown later, curing involves principally the two familiar 
physiological processes of respiration and of the translocation of 
mobile nutrients. Some investigators have preferred to regard the 
respiration phenomena as essentially pathological in character, and 
this view seems logically correct. The stalk and its leaves or the 
leaves alone, as the case may be, after harvesting are deprived of the 
water solution from the root system and for the most part are de- 
prived of sunlight. Since respiration continues, the living cells of 
the leaf are subjected to a process of starvation, and the degree to 
which the starvation proceeds is largely dependent on the rate of 
drying. As a matter of fact, however, the general character of the 
changes in composition during the curing, due to respiration, is very 
much the same as in normal respiration. As would be expected, the 
prevailing temperature and humidity play an important r61e in the 
process. The other important phenomenon, translocation, involves 
the movement of soluble materials from the leaf web, through the 
veins, into the midrib, and, if the leaf is attached to the stalk, thence 
into the latter. With one or two exceptions, investigators have over- 



STUDIES ON THE CURING OF LEAP TOBACCO. 3 

looked the importance of translocation when the leaf is cured on the 
stalk. 

It is, of course, well known that during the growth and development 
of the plant there is a movement of the products of photosynthesis, 
rendered soluble by enzyms when necessary, from the more mature 
leaf through the stalk to the younger growing parts. Essentially 
the same thing takes place after the cut plant has been placed in the 
barn, except that the materials transported are derived wholly from 
the surplus food supply of the leaf. While the leaf web perishes in a 
few days, the midrib remains alive for longer periods and the stalk 
may remain perfectly green for several weeks. Secondary shoots, or 
suckers, developing in the leaf axils, may be found growing at the 
end of several weeks, and the necessary food supply for the stalk and 
the suckers is derived from the leaf surplus. An interesting con- 
firmation of this phenomenon is found in the case of excessive mois- 
ture prevailing in the barn during the later stages of curing, a condition 
which leads to the decay of the leaf known as pole-sweat. The 
excessive moisture causes the dying leaf cells to retain more water, 
thus facilitating the more complete translocation of food materials 
into the stalk. Under these circumstances the so-called absciss- 
layer is formed at the juncture of the midrib with the stalk, so that 
the leaf is cast off as a useless appendage. Under normal curing 
conditions the leaves remain firmly attached to the stalk. 

LOSS IN WEIGHT OF DRY MATTER IN AIR CURING WHEN THE LEAF 

IS PRIMED. 

The first problem met with in a physiological study of curing is the 
total loss in dry weight which occurs in the process. So far as we 
know, no accurate determinations have been previously made on this 
point, at least in this country. Because of the important r61e of 
translocation in curing, the loss in weight depends largely on the 
method used in harvesting the tobacco. So far as it relates to loss in 
weight of the whole leaf, translocation can play no part when the 
leaf is separated from the stalk in harvesting. 

Our experiments cover the crop years of 1908 to 1911, inclusive, a 
period of four years, and were confined to the cigar-wrapper-leaf 
section of Connecticut, the experimental material all being obtained 
from the farm of W. S. Pinney, Suffield, Conn. The types of tobacco 
included in the experiments are the Havana Seed, the Halladay, and 
a so-called John Williams broadleaf . The Havana seed is one of the 
old standard types of domestic cigar-wrapper leaf and the Halladay 
is a new type developed from a cross of Havana seed on Sumatra. 
The history of the John Williams type of broadleaf is not known, but 
it differs decidedly from the ordinary broadleaf, and its habits of 
growth strongly suggest its origin from a cross of the latter on Cuban. 



4 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 

In gathering the experimental material each year, a sufficient num- 
ber of representative plants was selected to give about 200 ripe leaves 
near the bases of the plants, six or eight leaves being taken from each 
plant. The leaves were taken in pairs, each alternate leaf being placed 
in one lot and the other leaves in a second lot, the aim being to have 
each leaf in the one lot represented by a duplicate in the second lot. 
For the success of the experiment it is essential that the total dry 
weight and also the average composition of the two lots of leaves 
be practically the same. The detailed examination of the material 
gathered in the manner described indicates that these requirements 
have been satisfactorily met. A3 promptly as possible after harvest- 
ing the leaves the midribs were completely removed from the lot 
which was used to obtain the original dry weight. This was done to 
prevent any flow of cell sap between the leaf web and the midrib 
during the drying. The split leaves as well as the midribs were at 
once placed in a large drying oven and maintained at a temperature 
of about 80° C. until all were completely dry. The temperature em- 
ployed rapidly kills the protoplasm, and comparative tests with other 
methods of killing, such as plunging in boiling absolute alcohol, 
showed that the respiration changes during the drying were too small 
to be of significance for our purposes. (See p. 35.) The dry weights of 
the leaf web and the midribs were obtained and the material preserved 
for analysis. The second lot of leaves was placed in the barn for 
curing in the usual way without removing the midribs. When the 
cured leaves were ready for examination the leaf web was removed 
from the midrib, the dry weights obtained, and the material preserved 
for analysis. 

As has been stated, observations were made for a period of four 
consecutive years of the loss of dry matter in curing when the leaves 
are harvested by picking them from the stalk. The detailed results 
of these experiments are shown in section A of Table I (p. 5). In the 
case of the 1908 material the curing was stopped before the midribs 
had cured, but the curing of the leaf web was practically complete. 
In 1910 a special test of partial curing was made (Table I, fourth 
column) and in this case the curing was stopped while the larger veins 
and midribs were still uncured. In 1911 a test was made of the effeot 
of artificial heat on the curing. 



STUDIES ON THE CUEING OF LEAF TOBACCO. 5 

Table I. — Loss in dry weight in air curing tobacco leaves: (A) by the priming method, 

(B) by curing on the stalk. 



Tobacco leaves. 



A. — Leaves cured by the priming method. 



Havana Seed; 1908 
(partially cured). 



Leaf 
web. 



Stems. 



Whole 
leaf. 



Halladay; 1909. 



Leaf 
web. 



Stems. 



Whole 
leaf. 



Halladay; 1910. 



Leaf 
web. 



Stems. 



Whole 
leaf. 



Weight of 100 dry leaves: 

Uncured grams. . 

Cured do 

Loss of weight in curing, per 
cent 



Leaves: 

Uncured per cent . . 

Cured do 

Weight of pure ash in 100 
leaves: 

Uncured grams. . 

Cured do 

Apparent gain or loss of ash 
in curing per cent.. 

Loss of organic matter in cur- 
ing * per cent.. 



409.5 
329.4 



19.6 



72.5 
67.6 



44.9 
43.9 



-.24 
19.6 



155.1 
157.5 



27.5 
32.4 



26.9 
26.3 



- .38 



»-1.6 



564.6 



13.8 



100 
100 



71.9 
70.2 



13.8 



335.2 
306 



8.7 



74.1 

75.7 



51.2 
55.3 



+1.20 



117.2 
98 



16.4 



25.9 
24.3 



26.7 
25.2 



-1.28 



452.4 
404 



10.9 



100 
100 



77.9 
80.5 



+ .57 



294.8 
256.4 



13 



70.8 
72.2 



38.4 
41.4 



+1.02 
13.6 



416.2 
355 



14.7 



100 
100 



61.7 
63.6 



+ .45 
14.7 





A. — Leaves cured by the priming method. 




Halladay; 1910 
(partially cured). 


John Williams broadleaf. 


Tobacco leaves. 


1911-A (artificial heat 
applied). 


1911-B (no artificial 
heat applied). 




Leaf 
web. 


Stems. 


Whole 
leaf. 


Leaf 
web. 


Steins. 


Whole 
leaf. 


Leaf 
web. 


Stems. 


Whole 
leaf. 


Weight of 100 dry leaves: 

Cured do 

Loss of weight in curing, per 


269.3 
234.3 

13 

69.1 
68.4 

34 
36.3 

+.85 
13.5 


120.7 
108.3 

10.3 

30.9 
31.6 

22.3 
21.4 

-.74 
9.1 


390 
342.6 

12.2 

100 
100 

56.4 
57.6 

+.31 
12.2 


402 
356.8 

11.2 

77.8 
80.3 

48.9 
53.4 

+1.12 
12.1 


114.8 
87.6 

23.7 

22.2 
19.7 

23.8 
21 

-2.43 
19.1 


516.8 
444.4 

14 

100 
100 

72.7 

74.4 

+.33 
14 


402 
356.5 

11.3 

77.9 
80.4 

48.3 
. 52.2 

+.97 
12.2 


114 
87.8 

23 

22.1 
19.6 

24.2 
20.9 

-2.89 
19.9 


516 
444.3 

13.9 


Leaves: 

Cured do 

Weight of pure ash in 100 
leaves: 

Cured do 

Apparent gain or loss of ash 

Loss of organic matter in 
curing percent.. 


100 
100 

72.5 
73 

+.11 
13.9 



i Represents gain. 

» These figures are arrived at by deducting from the total loss in weight the apparent translocation of ash 
between leaf tissue and stem. See page 6. 



BULLETIN" 79, U. S. DEPARTMENT OP AGRICULTURE. 



Table I. — Loss in dry weight in air curing tobacco leaves: (A) by the priming method, 
(B) by curing on the stalk — Continued. 



Tobacco leaves. 



B. — Leaves cured on stalk. 



Havana Seed; 1908 
(partially cured). 



Leaf 
web. 



Stems. 



"Whole 
leaf. 



Halladay; 1909. 



Leaf 
web. 



Sterns. 



Whole 
leaf. 



Halladay; 1910. 



Leaf 
web. 



Stems. 



Whole 
leaf. 



Weight of 100 dry leaves: 

Uncured grams. 

Cured do. . . 

Loss of weight in curing, per 
cent 

Leaves: 

Uncured per cent. 

Cured do... 

Weight of pure ash in 100 
leaves: 

Uncured grams. 

Cured do. . . 

Loss of ash in curing , per cent 

Loss of organic matter in 
curing per cent. 



437.1 
312.4 



28.6 



72.5 
70 



45.3 
41.4 
.89 



27.7 



165.9 
134 



19.2 



27.5 
30 



28.4 
26.4 
1.20 



603 
446.4 



26 



100 
100 



73.7 
67.8 



25 



342.9 
238.1 



30.6 



70.2 
69.5 



42.3 
40.3 
.59 



30 



145.4 
104.6 



28.1 



29.8 
30.5 



27.9 
23.1 
3.31 



488.3 
342.7 



29.8 



100 
100 



70.1 
63.4 
1.38 



297.6 
230 



22.7 



70.7 
72.6 



38.6 
37.3 
.43 



22.3 



123.1 
86.7 

29.6 



29.3 
27.4 



23.2 
18.6 
3.74 



420.7 
316.7 



24.7 



100 
100 



61.9 

55.9 

1.42 



23.3 



The content of pure ash is of special interest as serving as a check 
on the original uniformity in size and composition of the uncured 
and cured leaves of each series, since there could be no actual loss of 
ash from the whole leaf. The differences found between the uncured 
and the cured leaves are so small as to be negligible, and they furnish 
strong evidence of the uniformity in size and composition of the 
original duplicate samples. We are safe, therefore, within very 
narrow limits, in regarding the observed differences in weight be- 
tween the uncured and cured leaves as representing the true loss in 
weight of dry matter during the curing process. 

Regarding the total loss in weight of the whole leaf, it will be seen 
that the values ranged from about 11 to about 14.5 per cent when 
the curing was completed. In the case of the 1909 sample of Halla- 
day tobacco the loss is undoubtedly below normal, and the low value 
for the whole leaf is due mainly to the slight loss in weight of the 
leaf web. It is not known to what extent unfavorable weather 
conditions during the curing may have influenced the result, but by 
reference to Table IV, section A (p. 18), it will be seen that the sam- 
ple was very low in starch content, and this constituent is the most 
important of all as regards loss in weight in curing. (See also p. 31.) 
Disregarding this sample, the loss in weight in the experiments is 
surprisingly uniform in view of the differences in types of leaf and 
the varying weather conditions during the curing. In the two cases 
where the curing was interrupted before it was complete, the loss in 
weight of the whole leaf was nearly as great as in complete curing, 
showing that the principal changes in composition to which the loss 
in weight is due proceed rapidly. In the case of the Havana Seed 



STUDIES ON THE CUEING OP LEAF TOBACCO. 7 

sample (1908) the loss would undoubtedly have been considerably 
greater had the stems been permitted to cure, as is to be expected, 
because of the relatively high starch content in this sample. For 
the types of leaf considered, the average loss in weight in dry matter 
during the curing of the picked leaves may be placed at about 12 to 
15 per cent. 

The data presented in Table I, section A, relate only to types of 
tobacco adapted to and grown under conditions favorable to the 
production of cigar-wrapper leaf, which is relatively very thin and 
light. This class of tobacco is harvested in a less ripe condition 
than are other classes of leaf, so that a lower content of starch is to 
be expected in the leaves when harvested. For these reasons the 
loss in dry weight in curing is greater in other classes of tobacco, and 
in the case of the export types losses in weight as high as 38 to 40 
per cent have been observed. The loss in weight in curing varies with 
the variety or type grown, the conditions under which the tobacco 
is grown, the degree of ripeness when it is harvested, and also with 
the conditions under which the curing takes place. The effects of 
these factors on the loss in weight are due to their influence on the 
composition of the leaf before or after the curing, particularly on 
the content of starch. 

LOSS IN WEIGHT OF DRY MATTER IN AIR CURING WHEN THE LEAF 
IS CURED ON THE STALK. 

The experiments relating to the loss in weight when the leaves are 
cured on the stalk cover the crop years of 1908 to 1910, inclusive, 
a period of three years, and the experimental material was obtained 
from the same fields as was that used in the preceding experiments. 
The stalks of the plants used were not split in harvesting, but were 
hung in the barn in the usual manner for curing cigar tobaccos. 
Every effort was made to have the experimental material directly 
comparable with that used in the preceding experiments for the 
same years. Plants were selected which were as nearly as possible 
like those used for the experiments in priming. Beginning near the 
base of the plant each alternate leaf was picked off, taking three or 
four leaves from each plant and leaving all of the remaining leaves 
intact. The stalks were then harvested and placed in the barn for 
curing. The midribs were promptly removed from the picked leaves 
and both the leaf web and the midribs completely dried, as in the 
previous experiment. The dry weights of the leaf parts were recorded 
and the material preserved for analysis. When the leaves attached 
to the stalks were cured the weights of the leaf web and midribs were 
likewise obtained and the material kept for further examination. 
As in the case of the experiments in priming, the leaves were removed 
from the stalks in the 1908 experiment before the midribs were 
fully cured. With the possible exception of the 1909 material, the 



8 



BULLETIN 79, IT. S. DEPARTMENT OP AGRICULTURE. 



ash content and the ratio of leaf web to rib in the uncured leaves, as 
well as the detailed analyses later reported, show conclusively that 
the original samples used for stalk curing were very similar to the 
corresponding samples used in curing by priming. 

The results of the three-year experiment are set forth in detail in 
section B of Table I. It will be seen at a glance that the loss in weight 
of the whole leaf in curing on the stalk is far greater than when the 
leaves are separated from the stalks. The figures run from about 25 to 
30 per cent, or approximately double those for curing the picked leaves. 
In the 1908 sample the total loss in weight would have been somewhat 
greater had the stems been given sufficient time for complete curing. 
The loss in weight in stalk curing is greater in both leaf web and rib 
than when the picked leaves are cured. It will be seen that the 
apparent loss in pure ash is positive and marked in all cases in both 
the leaf web and the ribs, showing conclusively that a portion of the 
ash passes into the stalk during the curing. 

EFFECT OF SPLITTING THE STALK ON THE LOSS OF WEIGHT IN AIR 

CURING. 

In some tobacco districts the stalk is split longitudinally from the 
top down the greater part of its length at the time the plant is 
harvested. Under these conditions the stalk can not remain alive 
in the barn as long as when it is merely severed from the rootstock, 
and it is to be expected that the phenomenon of translocation would 
be less important. A special experiment was carried out to secure 
information on this point. 

Two similar lots of 10 plants each were selected, and the stalks of 
one lot were split in the manner followed by growers. Each alternate 
leaf was picked from the plants in both lots, and the two lots of leaves 
thus obtained were cured separately. The leaves remaining on the 
stalks were cured under the same conditions as the primed leaves. 
When the curing was complete the dry weights were obtained as in 
the preceding experiments. At that time the unsplit stalks were 
still green, while the split stalks had largely dried out. 

Table II. — Loss of dry weight in air curing as affected by splitting the stalk in harvesting. 





Stalks split in harvesting. 


Stalks not split in harvesting. 


Air-cured leaves. 


Leaf 
web. 


Stems. 


Whole 
leaf. 


Leaf 
web. 


Stems. 


Whole 
leaf. 


Weight of 50 leaves: 

Cured on stalk grams. . 

Difference in loss of weight between stalk 
curing and curing picked leaves, per 


177.9 
219.5 

18.9 

71.8 
73 


70.1 
81.1 

13.6 

28.2 

27 


248 
300.6 

17.4 


176.5 
227 

22.2 

72.1 
72.8 


68.3 
84.6 

19.3 

27.9 
27.2 


244.8 
311.6 

21.4 


Leaves consisted of: 













STUDIES ON THE CURING OF LEAF TOBACCO. 9 

The results of the experiment are shown in Table II. While the 
actual number of leaves in each lot was 58, the results are calculated 
on a basis of 50 leaves for convenience in comparing with the other 
experiments. The experiment, of course, does not show the total 
loss in weight in curing in any case, but other experiments with similar 
material from the same field indicate that the loss in weight of the 
picked leaves must have been more than 20 per cent. The type of 
tobacco and the stage of ripeness account in all cases for the larger 
losses in weight than were obtained with the cigar types. Since 
only a single experiment was made and a rather small number of 
leaves used, the results can be taken as only approximately correct. 
These results indicate that when the stalk is split in harvesting, the 
loss in weight in curing is less than when the stalk is not split, but, 
nevertheless, the loss is much greater than when the leaves are picked 
from the stalk. 

COMPOSITION OF CIGAR- WRAPPER LEAP BEFORE AND AFTER CURING. 

The material obtained in connection with the data presented in 
Table I was subjected to analysis to ascertain the nature of the 
changes in composition which take place in air curing and to which 
the losses in dry weight are due. Because of the variations in the 
composition of the leaf at the time of harvesting, it is obviously 
essential that the material chosen for study shall be obtained under 
such conditions as will insure original uniformity in the composition 
of the uncured and cured samples. That this has been very closely 
attained in the above-mentioned material is shown in the values ob- 
tained for those constituents which undergo no change in the curing. 

LEAF HARVESTED BY PRIMING. 

The samples 1 used in these experiments cover the curing seasons 
of 1908 to 1911, inclusive, and include cases in which the curing was 
not fully completed. Although the midrib is never removed prior to 
curing, it has little or no value in manufacturing and, moreover, 
differs decidedly in composition from the leaf web, so that for present 
purposes it is necessary to consider the two leaf parts separately. 
The cured leaf always contains more or less water, depending on the 
type in question and on atmospheric conditions, but to simplify 
matters all results have been calculated to a water-free basis. 

PREPARATION OF MATERIAL AND METHODS OF ANALYSIS EMPLOYED. 

To pulverize the material for analysis, the leaf web was simply passed 
through a 60-mesh wire sieve. The stems were prepared by grinding 
to a fine powder in an iron mortar. The water content of the sample 
was determined by drying over sulphuric acid, as recommended by 

1 For details as to the methods followed in selecting and gathering the samples, the type of leaf used, etc., 
seep. 3. 

29731°— 14 2 



10 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 

Kissling. The pure ash, the carbohydrates, including starch, reducing 
sugars, pentosans, and crude fiber, and the several nitrogenous con- 
stituents were determined by the following methods: 

Pure ash. — The tobacco was incinerated in the usual manner in a 
platinum dish with a cover, care being taken to avoid fusing the ash. 
The pure ash is obtained by correcting for carbon dioxid, carbon, and 
sand. 

Starch. — Rather than attempt to determine starch directly by the 
diastase method it was preferred to obtain the total of the carbo- 
hydrates hydrolyzed by hydrochloric acid, using the official method, 
and to dete rmin e also the pentosans. It is thought that for purely 
comparative results this method is satisfactory, and nearly all pre- 
vious analyses of tobacco for starch which the writers have seen have 
been based on this method of the direct hydrolysis with acid, but 
usually without determining the pentosans. 

Pentosans. — The determinations were made by the official method, 
the phloroglucin being calculated to pentosan by Krober's tables. 

Reducing sugars. — Since nicotine, even in a moderately concen- 
trated solution, exerts a reducing action on Fehling's solution, it is 
removed before preparing the solution for the determination of reduc- 
ing sugars. This is done by moistening 5 grams of the tobacco with 
5 c. c. of a 5 per cent solution of caustic potash in absolute alcohol 
and digesting the mixture in a flask with 100 c. c. of absolute ether. 
The reducing sugar is then extracted with 60 per cent alcohol, the 
alcohol removed by evaporation, the water solution made up to vol- 
ume, clarified with normal lead acetate, and the sugar determined as 
glucose by the Allihn method. 

Crude filer. — The official method, as modified by Sweeney and by 
Kennedy, was employed. 

Nonvolatile organic acids. — The method of Kissling 1 was followed 
for the determination of oxalic, citric, and mafic acids. We have 
found it necessary, however, to increase by at least 25 per cent the 
quantity of sulphuric acid recommended by Kissling to be added to 
the tobacco, to insure the liberation of all the organic acids. This 
was particularly true of the cured samples, from which only very 
small portions of the oxalic acid could be extracted when only 10 
grams of a 20 per cent sulphuric-acid solution were added to 10 grams 
of the tobacco. 

Protein nitrogen. — Tests having shown that the method of Mohr 2 
gives excellent results for the purpose in view, it was followed in 
preference to the official (Stutzer) method. In this process the 
tobacco is simply boiled with a dilute acetic-acid solution, filtered 

1 Kissling, Richard. Beitrage zur Chemie des Tabaks. Zur Tabakanalyse. Chemiker-Zeitung, Jahrg. 
28, No. 66, p. 775-776, 1904. 

1 Mohr, E. C. J. Gepfliickter und am Stamme getrockneter Tabak. Die Landwirtschaftlichen Ver- 
Suchs-StatioDen, Bd. 59, p. 274, 1903. 



STUDIES ON" THE CURING OF LEAF TOBACCO. 11 

cold, and, after washing with hot water acidified with acetic acid, the 
nitrogen in the residue is determined by the Kjeldahl method. Com- 
parative tests of cured and uncured samples of tobacco show that the 
Stutzer method regularly gives results about 0.2 per cent higher than 
the Mohr method. The protein is estimated by multiplying the 
nitrogen obtained as indicated by the usual factor, 6.25. 

Nicotine. — This constituent was determined by the method described 
in Part VII of Bureau of Plant Industry Bulletin No. 102, entitled 
"A New Method for the Determination of Nicotine in Tobacco," tests 
having shown that this process gives as accurate comparative results 
as does the well-known Kissling method. 

Nitric acid. — The method of Kissling * was followed in this deter- 
mination. 

Ammonia. — This constituent was determined in the filtrate from 
the protein nitrogen by the Folin method as modified by Pennington 
and Greenlee. 2 Under the conditions, only traces of nicotine are car- 
ried over into the receiver by the air current. However, in our 
determinations the results were corrected by running check solutions 
containing the same quantities of nicotine as were known to be con- 
tained in the solutions from the tobacco samples. The temperature, 
rate of air current, etc., were kept as uniform as possible in making 
the determinations. 

Amid and amido nitrogen. — This value was obtained by taking the 
difference between the total nitrogen and the sum of the protein* 
nicotine, nitrate, and ammonia nitrogen. The figure obtained was 
multiplied by 4.8 (the approximate factor for asparagin) for amid and 
amido compounds. 

Total nitrogen. — The official Gunning method, as modified for 
nitrates, was used. 

RESULTS OBTAINED IN THE FOUR- YEAR EXPERIMENT. 

In section A of Table III (p. 12) will be found the results of the 
analyses of the leaf samples previously described. The leaf web and 
the stems or midribs were, of course, analyzed separately, and the 
results for the whole leaf were calculated from the ratio of leaf web 
to stem in each case. As a matter of convenience, the ripe, uncured 
leaf is designated in the table as "green." 

The content of pure ash of the cured leaves is higher than that of 
the uncured leaves in proportion to the loss in dry weight in curing, 
since there can be no change in the quantity of ash during the curing. 
While the green leaves contain considerable but quite variable quanti- 
ties of starch, the cured leaves contain practically none, as shown by 

i Kissling, Richard. Handbuch der Tabakkunde, des Tabakbaues und der Tabakfabrikation. Aufl. 
2, Berlin, 1905, p. 78. 

* Pennington, M. E., and Greenlee, A. D. An application of the Folin method to the determination of 
the ammoniacal nitrogen in meat. Journal, American Chemical Society, v. 32, p. 561-568, 1 rig., 1910. 



12 



BULLETIN 79, U. S. DEPARTMENT OF AGRICULTURE. 



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STUDIES ON THE CURING OF LEAF TOBACCO. 15 

the iodin test. Cigar-wrapper-leaf types contain less starch at the 
time of harvesting than other commercial types of leaf, because the 
former are harvested at a less mature stage and are produced under 
conditions less favorable to the accumulation of starch during the 
ripening period. Muller-Thurgau 1 has shown that in some cases 
fully ripe European-grown tobacco leaves may contain upward of 
40 per cent of starch, and we have found this to be true of some 
samples of our export types. (Compare pp. 35 and 38). 

One of the most marked physiological differences between the 
green and cured leaves is the content of protein insoluble in dilute 
acid. In all cases the protein content of the cured leaves is much 
less than that of the uncured leaves. 

The content of nitric acid in the green and in the cured leaves is 
about the same. The green leaves at most contain only traces of 
ammonia, while the cured leaves contain considerable quantities. 
The cured leaves contain relatively much larger quantities of amid 
and amido compounds than the green leaves. The relative content 
of total nitrogen is somewhat less in the green than in the cured 
leaves. 

LEAF HARVESTED ON THE STALK. 

The method followed in the preparation of the material and the 
methods of analysis employed were the same as for the leaves har- 
vested by priming. The original material was chosen with a view to 
obtaining samples which would be duplicates, essentially, of those 
used in the preceding experiments, in order that the stalk-cured 
leaves might be strictly comparable with those cured after being 
picked from the stalk. It is, of course, a simple matter to check by 
analysis the original uniformity of the corresponding lots of the green 
leaves in each case, since these were detached from the stalks, the 
leaf web separated from the midribs, and the leaf parts quickly dried. 
This can not be done so readily, however, with the two lots of cured 
leaves, because of the fact that when the leaves are cured on the 
stalk there is a well-defined movement of certain constituents from 
the leaf into the stalk, causing an additional loss in weight, which can 
only be determined by direct experiments, as reported in Table I, 
which require that the green and the cured leaves shall possess the 
same original weight. 

RESULTS OBTAINED IN THE THREE- YEAR EXPERIMENT. 

The comparative composition of cigar-wrapper leaf cured on the 
stalk and of the corresponding uncured leaf is shown in section B of 
Table III. As in the primed leaves, the ash content of the whole leaf 
is higher in the cured than in the uncured leaves. The cured leaves 

1 MiMer, Hermann ( Thurgau). Ueber das Verhalten von Starke und Zucker in reifenden und trock- 
nenden Tabaksblattern. Landwirstchaftlicha Jahrbucher, Bd. 14, p. 485-512, 1885, 



16 BULLETIN 79, U. S. DEPARTMENT OP AGRICULTURE. 

are again practically free from starch and reducing sugars, except 
where the curing was incomplete. The difference as regards proteiD 
is similar to those noted in the cured and uncured leaves in the pre- 
ceding experiments. The differences with reference to amid and 
amido compounds are somewhat variable, but it is evident that the 
cured leaf does not contain appreciably larger quantities of these 
constituents, relatively, than the green leaf, and the same is true as 
to ammonia. It is clear that the cured leaves contain considerably 
less total nitrogen than the green leaves. 

Analyses of cured samples of our more important commercial types 
of leaf tobacco have been published by several investigators, 1 but 
none of them has included the comparative composition of the corre- 
sponding uncured leaf. The results of Moore and of Carpenter indi- 
cate that the cured leaf of the bright flue-cured type is quite low in 
ash content, and it should be added that we have had occasion to 
examine a number of samples grown in eastern North Carolina which 
contained only 6 or 7 per cent of crude ash in the leaf web. In this 
type the cured leaf appears to be practically free from starch, but the 
content of reducing sugars is quite high (16 to 18 per cent), while the 
content of cellulose is decidedly low, particularly in the leaf web. 
The leaf contains moderate quantities of nicotine, practically no 
nitrate, and is very low in protein, as would be expected from the 
light color. White Burley, which is an air-cured type, is uniformly 
high in ash content, according to these authors. The cured leaf 
appears to be free from starch and reducing sugars and is relatively 
high in content of cellulose. The content of nicotine is high, the 
content of nitrate is considerable, and the content of protein is high. 
It is interesting to note that Burley closely resembles the cigar- 
wrapper-leaf types in composition in respect to all of the above- 
mentioned constituents. It is also interesting to note that the peculiar 
chlorotic appearance of this type when growing in the field is not 
associated with a low content of organic nitrogenous substances. 
The dark fire-cured export types of Virginia, Kentucky, and Tennessee 
are rather high in ash content, free from starch, low in reducing 
sugars, 2 and somewhat low in cellulose. These types are quite high 
in nicotine, usually low in nitrate, and high in protein, as is to be 
expected from the dark color of the cured leaf. The one sample of 

1 Moore, G. E. Report on the chemistry of American tobaccos. In Killebrew, J. B., Report on the 
culture and curing of tobaccos in the United States, p. 269. TJ. S. Department of the Interior, Census 
Office, Report on the Productions of Agriculture, Tenth Census, 1880. 1883. 

Chemical changes in tobacco during fermentation. Connecticut Agricultural Experiment Station, 16th 
Annual Report, 1892, p. 29-30. 1893. 

Winton, A. L., Ogden, A. W., Mitchell, W. L., and Jenkins, E. H. Effects of fertilizers on the compo- 
sition of wrapper leaf tobacco. Connecticut Agricultural Experiment Station, 20th Annual Report, 1896, 
p. 325-326. 1897. 

Carpenter, F. B. Types of tobacco and their analyses. North Carolina Agricultural Experiment 
Station, Bulletin 122, p. 331-366, 1895. 

1 Only two samples reported as to starch and sugars. 



STUDIES ON THE CUEING OF LEAP TOBACCO. 17 

Maryland export leaf reported is of interest chiefly because of its 
unusually high content of cellulose, since this type is characterized 
by its "chaffiness." The analyses of cigar-wrapper leaf reported by 
Jenkins and Winton are fairly comparable with our results, shown 
in Table III, since the material was grown in the same locality and the 
results obtained in the two cases are not essentially different. 

CHANGES IN COMPOSITION OF LEAF TOBACCO IN AIR CURING. 

While the data presented in Table III show the comparative 
composition of cured and uncured leaf tobacco in the form there 
presented, they do not properly bring out the changes in composition 
which take place during the curing. As shown in Table I, there is 
a marked but variable loss of dry weight in curing, and it is evident 
that the simple comparison of the percentage composition of cured 
and uncured leaves does not give a correct index as to the actual 
changes in content of the various constituents involved in the curing. 
As pointed out by Mohr, 1 nearly all early investigators have made 
this error in collecting their data, with the result that many of their 
conclusions are entirely erroneous. There are two ways in which 
this difficulty can be overcome. One method is to base all compari- 
sons on unit areas of the leaf rather than on weights, and this is 
undoubtedly the most satisfactory method in dealing with a small 
number of leaves, but where larger quantities of material are 
required the procedure requires much time and labor. A second 
method, which has been followed in our experiments, is to collect 
the leaves in pairs, so that each leaf which is cured shall have a dupli- 
cate which is quickly dried and weighed, as was described on page 4. 
In this way the total loss in weight in curing is obtained simply 
by comparing the weights of the cured and uncured leaves, and it 
is only necessary to correct the results of the analysis of the cured 
leaves for the total loss of weight in curing. There are necessarily 
some individual variations in the leaf "pairs," so that this method is 
not entirely reliable when only a few leaves are used, but if the 
composite samples include a hundred or more leaves the individual 
variations are of little or no consequence. 

In Table IV we have corrected the results of the analyses of the 
cured leaf as shown in Table III for the respective loss in weight in the 
curing of each sample as shown in Table I, so that all results are cal- 
culated on the basis of the uncured leaf. We have added data show- 
ing the gain or loss of each constituent for the two leaf parts and for 
the whole leaf in each case. Table V presents in a similar manner 
the data for the total nitrogen and nitrogen in the various forms of 
combination found in the tobacco. 

1 Mohr, E. C. J. Gepfluckter und am Stamme getrockneter Tabak. Die Landwirtschaftlichen Ver- 
suctas-Stationen, Bd. 59, Heft 3/4, p. 256, 1903. 

29731°— 14—3 



18 



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STUDIES ON THE CUEING OF LEAP TOBACCO. 



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STUDIES ON THE CURING OP LEAF TOBACCO. 25 

In the experiments with picked leaves any apparent differences in 
the ash content of the whole leaf as between the green and cured leaves 
are, of course, due to slight differences in the composition of the dupli- 
cate samples and to experimental errors. As between the two leaf 
parts, however, it is to be observed that in every instance the leaf 
web appears to gain in ash content at the expense of the midrib dur- 
ing the curing. There is no doubt that this movement of mineral 
matter from stem to web takes place during the later stages of dry- 
ing, and tobacco growers are familiar with the discoloration fre- 
quently caused thereby in the leaf in the vicinity of the stem. The 
movement is doubtless due simply to diffusion and is not to be con- 
nected with the reverse movement due to physiological translocation. 
As is well known, the leaf web normally dies and dries long before the 
stem, and the latter finally collapses rather suddenly. The remain- 
ing cell sap then oozes out into the leaf web, causing the discoloration 
referred to. This movement of materials, occurring after the death 
of the protoplasm, is not large and is localized. In the experiments 
in stalk curing there is a loss of ash in curing in the leaf as a whole, 
which, of course, can not be due to respiration and can only be 
accounted for by the assumption that a portion of the ash has passed 
into the stalk. 

CHANGES IN THE CARBOHYDRATES. 

In both methods of curing, nearly all the starch disappears both 
from the leaf web and from the midrib during the process. We have 
been unable to obtain a reaction for starch by the iodin test in the 
cured samples. This is in accordance with the results of Muller- 
Thurgau already referred to. The more or less complete disappear- 
ance of starch is one of the most characteristic changes involved in 
curing, and the relative freedom from starch of the cured leaf is a 
measure of the completeness of the curing process. It will be seen 
also that in complete curing by either method practically all of the 
reducing sugars disappear. The incompletely cured samples of 1908 
reveal the fact, however, that the disappearance of starch precedes 
that of the sugars, as is to be expected, and, furthermore, that there 
is a temporary accumulation of sugars in the midrib, undoubtedly 
derived from the starch of the leaf web. It has been pointed out 
that analyses of flue-cured leaf have shown that under that system 
of rapid curing the leaf contains high percentages of reducing sugars, 
which are doubtless derived from the splitting up of starch, and the 
premature killing of the protoplasm prevents the oxidation of the 
sugars by respiration. 

Our results as a whole indicate that the pentosans, which, gener- 
ally speaking, are not physiologically plastic, undergo but little change 
in the leaf web, but in the stems there is a more decided decrease of 
these constituents. The crude-fiber content undergoes little or no 
change, except that in complete curing there appears to be a slight 



26 BULLETIN" 19, U. 8. DEPARTMENT OF AGRICULTURE. 

decrease in the stems, no doubt due to loss of pentosans or related 
hemicelluloses rather than to any change in true cellulose. 

CHANGES IN THE NONVOLATILE ORGANIC ACIDS. 

Tobacco leaves contain considerable quantities of oxalic, malic, 
and citric acids, and the changes which these undergo during the 
cining are interesting from the physiological point of view. That 
these acids are of importance in plant metabolism is generally recog- 
nized, but their role has not been fully determined. Because of then- 
close relationship to the amido acids, such as aspartic acid and 
asparagin, it seems reasonable to associate them with protein syn- 
thesis. It is generally believed, however, that oxalic, citric, and malic 
acids have their origin in the incomplete oxidation of sugars when 
respiration proceeds in the presence of a limited oxygen supply. It 
appears that under certain conditions these acids may be converted 
partially into sugars, on the one hand, and partially into carbon 
dioxid and water, on the other hand. So far as we know, no dis- 
tinction has been made heretofore as to the metabolic transforma- 
tions which these three different acids undergo in the plant, but our 
results with green and cured tobacco leaves show that they behave 
quite differently during the curing process, which involves essen- 
tially the phenomena of respiration and of translocation. 

It is evident that the content of oxalic acid is not changed during 
the curing, and this is equally true in both methods of curing. There 
is a decided loss of malic acid during the curing when the leaf is primed, 
as well as when it is cured on the stalk. Citric acid, on the other hand, 
undergoes no decrease during the curing by either method, and, in- 
deed, there is a considerable increase in content of the acid, which is 
surprising in view of the behavior of the malic acid. It is, of course, 
conceivable that the malic acid is partially transformed into citric 
acid, but a simpler view is that the citric acid resists oxidation to 
lower products more than the malic acid, so that during the process 
of partial oxidation of the sugars to acids there is a gradual accumu- 
lation of citric acid, while the malic acid is more completely oxidized 
to water and carbon dioxid. 

CHANGES IN THE NITROGENOUS CONSTITUENTS. 

Referring to Tables IV and V, it will be seen that the loss in protein 
in curing is very large in all cases, in some instances exceeding 60 per 
cent of the total. The marked decrease in protein content, like 
the disappearance of starch, is a characteristic change involved in 
curing, and the relative decrease is an index of the completeness of the 
curing. 

The decrease in starch content and in protein content furnishes a 
simple and reliable means of determining by chemical analysis the 
progress and the completeness of barn curing. 



STUDIES ON THE CURING OF LEAF TOBACCO. 27 

There is undoubtedly a considerable loss in nicotine content in 
curing due to simple volatilization, but all this loss is not shown in 
our experiments, for the reason that the green or uncured, as well 
as the cured, leaves were dried at about 80° C. and this temperature is 
sufficient to expel the more readily volatile portion of the nicotine. 1 
In the leaf as a whole there appears to be no marked change in the 
content of nitric acid in either method of curing. The indicated loss 
of nitrate in the stem is probably only apparent, at least in part, since 
about the same losses are indicated for curing the primed leaves as 
for curing on the stalk. The determinations of nitrate were based on 
the well-known method of reduction with ferrous chlorid in acid solu- 
tion and measurement of the oxid of nitrogen liberated. In all cases, 
however, it was found that with the green stems a sharp end reaction 
could not be obtained, for, after the principal reaction was com- 
pleted, a slow evolution of gas continued almost indefinitely, appar- 
ently due to some reaction other than the reduction of the nitrate. 
The values for nitric acid in the green stems are therefore somewhat 
too high, which would, of course, have the effect of indicating a loss 
of nitric acid in curing. That the results for the green stems are too 
high is further indicated by the fact that the sum of the protein, 
nicotine, and nitrate nitrogen as obtained somewhat exceeds the total 
nitrogen in the green stems. 

In the primed leaves there is a very marked increase in the amid and 
amido compounds, corresponding to the large decrease in protein. A 
considerable portion of these cleavage products of protein pass from the 
leaf web into the stem, which in the green condition contains practically 
none of these products. In the case of stalk-cured leaves there is no 
increase in amid and amido products, but, on the contrary, a con- 
siderable decrease, although the decrease in protein in this method 
of curing is even greater than in curing the primed leaves. Evi- 
dently the phenomenon of translocation is here an important factor. 
In the leaves cured by priming there is always a considerable loss of 
total nitrogen, which can not be due to translocation, and since there is 
no equivalent loss of nicotine the nitrogen doubtless escapes in the form 
of ammonia. The odor of ammonia is readily recognized in the cur- 
ing barns, and there can be no doubt that it is liberated during the 
curing process. In other words, the cleavage products of protein are 
further changed, with ammonia as one of the decomposition products. 
The observed increase in content of ammonia, therefore, represents 
only a portion of the total quantity formed during the curing, the 
amount which becomes fixed in the leaf doubtless depending on the 
quantity of free acid present. 

1 Garner, W. W. Relation of nicotine to the quality of tobacco. U. S. Department of Agriculture, 
Bureau of Plant Industry, Bulletin 141, p. 5-16, 1909. 



28 BULLETIN 19, U. S. DEPARTMENT OP AGRICULTURE. 

Considering collectively the changes in the various constituents 
involved in curing, we find in the case of the primed leaves that, 
where the analyses are complete, the sum of the various losses 
recorded, less the sum of the gains, gives a total loss amounting to 
from 70 to 90 per cent of that obtained in Table I; or, in other words, 
our analyses have accounted for this proportion of the constituents 
which are of importance from a quantitative standpoint. A very 
close agreement is not to be expected, since the factors used in cal- 
culating the protein and the amid and amido constituents are probably 
only approximately correct. The results of the analyses account for 
about 75 per cent of the loss in weight indicated in Table I, where 
the leaves are cured on the stalk. 

Aside from the observations made by Muller-Thurgau regarding the 
loss of starch and sugars in the curing, which have already been men- 
tioned, the only paper bearing directly on the changes in composi- 
tion during the curing, so far as known, is that of Behrens, 1 who, like 
nearly all previous investigators, was concerned mainly in a compari- 
son of the methods of curing on the stalk and of curing the primed 
leaves. He presents data, however, showing the comparative com- 
position of green and cured leaves. Since the total loss of weight in 
curing was not determined, the changes in composition can only be 
considered qualitatively. His analyses indicate the disappearance of 
starch and a decrease in sugars and protein nitrogen in curing. 
They show also a relative loss of total carbon and a relative gain in 
total nitrogen during the curing process. 

While little is known as to the identity of the individual com- 
pounds making up the groups of constituents involved in the curing 
changes, particularly as regards the protein group and their cleavage 
products, the general character and course of the transformations 
concerned can be considered as definitely established. The follow- 
ing scheme shows the general course of the changes common to both 
methods of curing which the several groups of constituents undergo 
during the curing process, the prime factor in effecting these trans- 
formations being respiration, although the phenomena of transloca- 
tion play a more or less important rdle, depending on the method of 
curing followed. 

Diagram showing the general course of changes during the curing process. 

[Oxalic acidl 
Starch >Sugars >\ Citric acid L (?)- -»Carbon dioxid and water. 



Pentosans. - I Malic acid J.—--" 

„-* 
.--Cn- 
Protem +l A f£2iE&!E' ao )- — -JcaX^dioxid. 

\ derivatives / ^Water. 

i Behrens, Johannes. Weltere Beitr&ge zur Kenntnis der Tabakpflanze. Die Landwirtschaftlichen 
Versuchs-Stationen, Bd. 43, p. 271-301, 18 



STUDIES ON THE CUEING OF LEAF TOBACCO. 29 

In the above scheme the changes which take place quantitatively 
are indicated by solid lines, and partial transformations are indicated 
by broken lines. The transformation of the sugars into nonvolatile 
organic acids is bracketed, for the reason that, although the sugars 
are quantitatively removed, it is not known to what extent the acids 
are formed as intermediate products of oxidation. There is some 
question as to whether citric acid is further oxidized during the curing 
process, and it has not been actually proved that nitrogen-free acids 
are formed by the hydrolysis of the amido derivatives of protein, 
although this seems highly probable. The scheme merely presents 
the course of events in the breaking up of the surplus food supply 
in support of respiration, and does not take into account the move- 
ments of the soluble products due to physiological translocation. 

It will be seen that the so-called ether extract, which is usually 
included in the analysis of agricultural products and which is intended 
to show the content of fat or oil, has not been considered in connec- 
tion with our studies on the changes in composition taking place 
during the curing. It has not been considered that this determina- 
tion would throw any light on the problems in hand, for the extract 
obtained from tobacco leaves is a hopelessly complex mixture, con- 
taining a portion of the nicotine, chlorophyll, and its decomposition 
products, tobacco resins, etc., and in reality containing at most very 
small quantities of constituents which could be properly called fat 
or oil. No methods are at present available for the quantitative sep- 
aration of the several constituents of the ether extract, and it is 
obvious that the crude extract would contain several constituents 
already accounted for in the analyses. 

The results which have been presented and discussed in the pre- 
ceding paragraphs apply more particularly to typical air curing. 
Samples A and B of 1911, in Tables IV and V, should bring out any 
differences in the final result of the curing when air curing is modified 
by the moderate use of artificial heat. As a matter of fact these 
duplicate samples, after curing, show almost exactly the same com- 
position; so that, although the moderate application of heat hastens 
the rate of curing, as shown by the appearance of the tobacco during 
the progress of the process, the final result, so far as shown by the 
analyses, is the same, whether or not the heat be applied. In the 
case of flue curing, where much higher temperatures are used, no 
comprehensive investigations have been made; but analyses of the 
cured leaves which have been reported show that the curing changes 
are of the same character as in air curing, the only difference being 
that in flue curing the transformations are less complete. In typical 
fire curing, in which the tobacco is only partially cured by the use of 
heat, the relative completeness of the chemical changes involved 
probably falls between that in air curing and that in flue curing. 



30 BULLETIN 79, U. S. DEPARTMENT OF AGRICULTURE. 

CURING THE LEAVES ON THE STALK COMPARED WITH CURING THE 

PICKED LEAVES. 

The relative merits of tlie two methods of curing have long been 
a subject of interest to agricultural investigators, both in this and 
in foreign countries, and the greater portion of the experimental 
work relating to tobacco curing which has been done has had special 
reference to this problem. Some of the earlier investigators main- 
tained that the leaf weighed more when cured on the stalk, because of 
a flow of soluble material from the stalk into the leaf. Others, how- 
ever, notably Nessler 1 and Behrens, 2 maintained that there was no 
particular difference in results as between the two methods of har- 
vesting and curing, either with reference to weight or to quality of 
the cured leaf. We are indebted to Mohr 3 for the first comprehensive 
and decisive study of the subject. Mohr brought out clearly the 
errors in the methods of procedure and in the interpretation of results 
made by previous investigators and proved beyond doubt that for 
the particular type of tobacco with which he worked (cigar-wrapper 
leaf) the leaf cured on the stalk loses in weight approximately 11 or 
12 per cent more than if cured after being picked from the stalk. 
This is equivalent to saying that a picked leaf after curing will weigh 
11 or 12 per cent more than would the same leaf if cured on the stalk. 
Mohr proved conclusively by analyses of the ash and other con- 
stituents that the increased loss in weight which occurs when the 
leaf is cured on the stalk is due not so much to a more intense respira- 
tion but rather to a translocation of nutritive material from the leaf 
into the stalk. 

Coming to our own experiments, by reference to Table I (p. 5) it 
is seen that with comparable material harvested and cured by the 
two methods in question during the years 1908, 1909, and 1910 the 
losses in dry weight by curing the leaves on the stalk were 12.2, 18.9, 
and 10 per cent, respectively, greater than the losses in curing the 
picked leaves. The larger indicated difference in loss of weight 
between the two methods for 1909 is to a great* extent due to the 
unusually small loss in weight of the picked leaves, and this in turn 
is fully explained by the abnormally low content of starch of the 
picked leaves at the time of harvesting. However, the average dif- 
ference between the losses in weight for the three years by the two 
methods of harvesting and curing is 13.7 per cent, taking the figures 
as they stand; and this value is in close agreement with Mohr's results 
for the same general type of tobacco, namely, cigar-wrapper leaf. 
On the other hand, Table II (p. 8) shows that the difference in loss 

i Nessler, J. Der Tabak, seine Bestandtheile und seine Behandlung, Mannheim, 1867. 

2 Behrens, Johannes. Weitere Beitrage zur Kenntnis der Tabakpflanze. Die Landwirtschaftlichen 
Versuchs-Stationen, Bd. 43, p. 280, 1894. 

' Mohr, E. C J. Gepfliickter und am Stamme getrockneter Tabak. Die Landwirtschaftlichen Versuchs- 
Stationen, Bd. 59, Heft 3/4, p. 253-292, 1903. 



STUDIES ON THE CUEING OP LEAF TOBACCO. 31 

of weight in curing between leaves harvested on the stalk and those 
picked from the stalk may be much greater with some of our manu- 
facturing and export types, which are grown under different con- 
ditions and harvested in a much riper state than the cigar-wrapper 
types. It will be seen that in stalk curing there was a loss of about 9 
to 10 per cent of the original content of pure ash, which is in close 
agreement with Mohr's results. In curing the primed leaves there 
can, of course, be no loss of ash. Our results show that, although 
the cured picked leaves contain little or no starch, the removal of 
insoluble carbohydrates is pushed considerably farther when the 
leaves are cured on the stalk. There is a more marked decrease of 
pentosans in stalk curing. There is no essential difference in the 
results as between the two methods with reference to sugar content, 
since in both cases there is a practically entire disappearance of 
sugars when the curing is complete. 

The compounds of nitrogen are decidedly the most important con- 
stituents of the leaf in regard to differences in the results of curing 
on the stalk as compared with curing the picked leaves. For the 
three years for which direct comparisons are made, the loss in protein 
nitrogen in the leaf web, and particularly in the midrib, was decidedly 
greater in stalk curing than in curing the picked leaves. Since the 
temperature employed in drying the samples was sufficient to expel 
the easily volatilized portion of the nicotine, no definite conclusion 
can be drawn as to the differences in loss of this constituent in the 
two methods of harvesting. The results regarding nitrate nitrogen 
are unsatisfactory, doubtless because of the difficulty in obtaining 
reliable results with the uncured material, as pointed out on page 28. 
As a whole, the results do not indicate a very marked translocation 
of nitrates into the stalk. As far as they were carried, our results 
indicate that ammonia is readily translocated into the stalk. 

In comparing the results of the two methods of curing with refer- 
ence to changes of composition, the most striking difference is to be 
found in the behavior of the nitrogenous cleavage products from the 
hydrolysis of protein. From 40 to 60 per cent of the protein is 
broken up during the curing process and, although the loss in total 
nitrogen in curing the picked leaves shows conclusively that a por- 
tion of the nitrogen of the decomposition products escapes as ammo- 
nia, the loss thus involved is but a comparatively small portion of 
the whole. The result is that there is a marked accumulation of 
amid and amido compounds in the cured picked leaves, the increase 
in this form of nitrogen amounting to 0.5 to 1.5 per cent of the leaf 
weight, or 100 to 400 per cent more than was contained in the uncured 
leaf. In the stalk-cured leaves, on the other hand, not only are the 
products resulting from the splitting of the protein completely 
removed, but a considerable portion of the amid and amido com- 



32 BULLETIN 79, U. S. DEPARTMENT OF AGRICULTURE. 

pounds originally present in the leaf are also removed in the process 
of curing. In stalk curing, the loss of nitrogen in these forms amounts 
to 35 to 45 per cent of the total protein and amid and amido nitro- 
gen, while in curing the picked leaves the direct loss of nitrogen in 
these forms by the splitting off and escape of ammonia averages 
less than 10 per cent of the total. In stalk curing, the content of 
amid and amido nitrogen alone is reduced by about 15 to 60 per 
cent, depending on the original content of these forms of nitrogen. 
As regards total nitrogen, the loss in curing the picked leaves is 
from 4 to 15 per cent of the total, while the loss in stalk curing is 
from 35 to 42 per cent. 

As regards the organic acids, there is no decided difference in the 
behavior of oxalic acid in the two methods of curing, and this is 
true also as to malic acid. Citric acid seems to accumulate to 
approximately the same extent whether the leaf is attached to the 
stalk or is detached during the curing. There is no satisfactory 
evidence that these acids undergo translocation in stalk curing. 

Summing up the more important differences in the results of 
curing the leaves on the stalk as compared with curing the picked 
leaves which are brought out in our experiments, it is seen that the 
loss in weight of dry matter is 10 to 15 per cent greater when the 
leaves are cured on the stalk. This difference is due mainly to the 
more complete removal of carbohydrates, including the pentosans, 
and of protein and, more particularly, to the translocation of the 
cleavage products of protein and of the mineral constituents from 
the leaf into the stalk. In stalk curing, in addition to the respira- 
tion activities which constitute the important factor in curing the 
picked leaves, the translocation of mobile materials from the leaf 
into the stalk assumes an important role. This translocation of 
materials from leaf to stalk in stalk curing constitutes, in fact, the 
essential difference between this method of curing and that in use 
after the leaves are removed from the stalk. Our results on this 
phase of tobacco curing agree closely with the conclusions reached 
by Mohr from his study of the subject. These results find additional 
support in the work of Johnson * relating to the composition of two 
lots of tobacco stalks, from one of which the leaves were removed at 
the time of harvesting, while the second lot was allowed to cure with 
the leaves attached. The analyses of the two lots of stalks show 
that those which were allowed to cure with the leaves attached 
gained approximately 30 per cent of their original content of total 
nitrogen, 36 per cent of their content of phosphoric acid, and 8 per 
cent of their content of potash. This gain in nitrogen, phosphoric 
acid, and potash can only be accounted for on the assumption that 

1 Johnson, S. W. Analyses of tobacco stalks when cut and after curing. Connecticut Agricultural 
Experiment Station, 16th Annual Report, 1892, p. 31-34. 1893. 



STUDIES ON THE CURING OF LEAF TOBACCO. 33 

these constituents were transported from the leaf into the stalk 
during the process of curing. It is evident that the phenomena of 
translocation in the curing of tobacco leaves attached to the stalk 
follow essentially the same laws as obtain during the growth and 
development of plants under normal conditions. The movement of 
reserve nutrients is from the leaf web through the veins and midrib 
into the stalk and normally thence to the younger growing parts. 
Only such constituents as are the most essential, physiologically, 
undergo translocation to a marked degree. 

ENZYMS IN TOBACCO CURING. 

It has been pointed out in the preceding pages that tobacco curing 
consists, primarily, in the hydrolysis of insoluble carbohydrates and 
proteins, followed by a partial or complete removal of the cleavage 
products by further hydrolysis and by oxidation and, in stalk curing, 
by translocation into the stalk. It is quite generally recognized that 
the immediate agencies effecting transformations of this character 
in the vital activities of the plant are enzyms. We have shown that 
starch and pentosans are converted into reducing sugars, which are 
then oxidized or translocated, and that protein is converted into the 
simpler amid or amido derivatives, from which, in turn, ammonia is 
split off. It seems probable, therefore, that diastases, cytases, and 
proteolytic and deamidizing enzyms take part in the curing of the 
tobacco leaf. It seems very probable also that the oxidases play an 
important part, particularly as regards the changes in color which 
the leaf undergoes in curing. 

We have not attempted to go into a study of the enzyms concerned 
in tobacco curing, except simply to bring out the fact that their 
activities are for the most part intimately associated with and de- 
pendent upon the presence of the living protoplasm. We have 
already pointed out that a ripe tobacco leaf will not cure properly, 
even under the most favorable conditions, if it has been previously 
subjected to very high or low temperatures or to the action of pro- 
toplasmic poisons. It has also been stated that the progress of the 
curing can be readily followed by determining at different stages the 
relative quantities of unchanged starch and protein contained in the 
leaf. The following experiments show by chemical methods that 
the premature killing of the protoplasm prevents the changes in 
composition which are essential to successful curing. 

In the first place, an experiment was carried out to determine the 
effectiveness of rapid drying at high temperatures in preventing these 
changes in composition. Two lots of leaves, containing 14 leaves in 
each lot, were selected in the manner described on page 4, and one 
of these lots was allowed to cure normally. The midribs were re- 



34 



BULLETIN 79, U. S. DEPARTMENT OP AGRICULTURE. 



moved from the second lot of leaves and the half of each leaf thus 
resulting was plunged into boiling absolute alcohol for a few minutes, 
while the second set of leaf halves was immediately placed in an air 
bath heated to 90° C. and dried. The results of the experiment are 
shown in Table VI. In the case of material killed with alcohol the 
results were corrected, of course, for the matter extracted by the 
alcohol. To facilitate comparison, the results are presented on a 
uniform basis of 14 whole leaves, exclusive of the midribs. 

Table VI. — Effectiveness of hilling fresh tobacco leaves at high temperatures, as compared 
with killing with hot alcohol in arresting changes in composition. 



1911 material. 



(a) 

Leaf web 

killed with 

alcohol. 



(6) 

Leaf web 
killed at 
high tem- 
perature. 



(c) 

Leaf cured 
normally. 



Dry weight of 14 leaves grams. . 

Loss of weight in curing per cent.. 

Starch do 

Protein nitrogen do 

Reducing sugars do 



26.64 
2.04 
1.21 



124.6 

1.3 

24.57 

2.13 

1.63 



97.5 

22.8 

5.17 

1.22 

3.86 



In the above table the results are calculated on a basis of the 
original dry weight of the leaves, as represented by a. These results 
show that, while subjecting the leaf to a temperature of 90° C. does 
not immediately stop all action upon the carbohydrates, this method, 
which was employed in all the experiments already described, answers 
satisfactorily for the purposes in view. Having established this point, 
the effect on the curing process of chloroforming the leaf was next 
studied. A lot of five ripe leaves was collected and their midribs 
removed. The one lot of leaf halves thus obtained was immediately 
dried at 90° C, as in the preceding experiment, while the second lot 
was exposed to chloroform vapors in a closed jar for a few minutes 
and then placed under the proper conditions for normal curing. After 
four days this material was also dried at 90° C. The results of the 
experiment are shown in Table VII. 

Table VII. — Effect of exposure to chloroform on the curing of tobacco leaves. 



1912 material. 




Dry weight of 5 half leaves grams. . 

Starch per cent. . 

Protein nitrogen do 



It is obvious that exposure to chloroform effectually prevents 
those changes in composition which are characteristic of normal 
curing and, indeed, the appearance and properties of leaves so 



STUDIES ON THE CUEING OF LEAF TOBACCO. 35 

treated clearly show that normal curing does not take place. Since 
these normal changes in composition are effected by hydrolytic 
enzyms, and since it is well known that the green leaves of plants 
normally contain these enzyms, it is not clear why protoplasmic 
poisons which do not inhibit the action of such enzyms should 
prevent the progress of the curing along these lines. Brown and 
Morris * considered this matter in connection with their investigations 
on the occurrence of diastase in the leaves of plants, but did not 
arrive at a satisfactory conclusion. They found that, although the 
diastatic activity of the leaf increases markedly when it is kept in 
darkness, even when a leaf has been subjected to this treatment 
there is no further decrease of starch after treatment with chloroform. 
Whatever the explanation of this phenomenon, it seems logical, as 
suggested by Brown and Morris, that partial starvation will lead to 
an increased formation by the leaf cell of enzyms designed to furnish 
the needed nourishment. We have found that such is the case as 
regards diastase in the curing of tobacco leaves. The method used 
for comparing the diastatic activity of fresh and partially cured 
leaves was that described by the above-named investigators, and 
consists essentially in digesting a given weight of the material with 
a 2 per cent water solution of soluble starch under proper conditions 
and with suitable controls. The increase in reducing sugars is 
taken as a measure of the relative diastatic activity. 

In the following experiments, after having obtained the leaf areas, 
one half of each leaf was chloroformed and dried at 35° C, while 
the remaining half of each leaf was maintained under normal curing 
conditions (slow drying in darkness and at moderate temperatures) 
for a period of 43 hours in experiment 1 and for one week in experi- 
ment 2. 

The material chosen for the first experiment was a single mature 
bottom leaf taken from a Connecticut Broadleaf plant grown in 
the greenhouse, and in the second experiment one bottom and two 
top leaves were taken from a mature plant of Yellow Pryor grown 
under normal field conditions. The cured material was chloroformed 
and dried in the same manner as the uncured. The diastatic activity 
was determined for equal areas and not equal weights of the cured 
and uncured material, and the results as reported are in terms of 
the weights of maltose formed by digesting 10 grams of the uncured 
samples chosen as standards and weights corresponding to an 
equal area of the other samples with 2 per cent soluble starch solu- 
tion for 48 hours at 30° C. It is necessary to use equal areas of leaf 
to correct properly for the loss in dry weight in curing. The results 
of these experiments are shown in Table VIII. 

» Brown, H. T., and Morris, G. H. Contribution to the chemistry and physiology of foliage leaves. 
Journal, Chemical Society [London], Transactions, v. 63, p. 604-659, 1893. 



36 BULLETIN 79, IT. S. DEPARTMENT OF AGRICULTURE. 

Table VIII. — Diastatic activity of uncured and partially cured tobacco leaves. 



Material. 


Total 
weight of 
material. 


Weight per 
square foot. 


Loss of 

weight in 

curing. 


Weight of 
leaf used. 


Relative 
diastatic 
activity. 


Experiment 1 (14 square inches of leaf sur- 
face used): 
A bottom leaf- 


Grams. 
6.47 
5.67 

7.634 
4.836 

8.536 
5.004 


Grams. 
5.124 
4.489 

7.354 
4.659 

7.940 
4.655 


Per cent. 


Grams. 
0.5000 
.4378 

.5000 
.3167 

.5398 
.3164 


4.41 


Cured half 


12.4 


5.48 


Experiment 2 (9.8 square inches of leaf sur- 
face used): 
2 top leaves— 


2.04 




36.7 


7.02 


A bottom leaf- 


2.48 


Cured half 


41.4 


6.50 







The above results show very clearly that there is a marked increase 
in the diastatic activity of tobacco leaves during the curing process. 
It seems probable that there is a similar increase in the proteolytic en- 
zyms during the curing, but no attempt was made to determine this 
point. 

TOBACCO CURING AS AFFECTED BY EXTERNAL CONDITIONS. 

Since respiration plays a fundamental r61e in tobacco curing, it is to 
be expected that the external conditions, notably the temperature, 
will have a decided influence on the curing process. The factors of 
importance in this connection are the temperature and relative con- 
tent of moisture, oxygen, and carbon dioxid of the surrounding 
atmosphere and the presence or absence of light. We have made 
some experiments on the relation of the first two of these factors to 
the rate of curing, using the quantities of starch and protein hydro- 
lyzed as a measure of the progress of the curing. 

EFFECT OF TEMPERATURE ON RATE OF CURING. 

In 1911 three lots of six leaves each were collected, using the pre- 
cautions already described in detail, to have the three lots strictly 
comparable. The stems were removed from the first lot of leaves (a) 
and the leaf web killed by plunging into boiling absolute alcohol, 
after which the leaf web and stems were dried at 80° C. The second 
lot of leaves (b) was placed in a bell jar and maintained at a temper- 
ature of approximately 10° C. (50° F.) for 24 hours, after which they 
were treated exactly like the first lot. The third lot (c) was similarly 
maintained at a temperature of approximately 24° C. (75° F.) for 24 
hours and then treated like the other two lots. In 1912 the experi- 
ment was repeated with two lots of five leaves each. The stems were 
removed from the first lot (a), one half of each leaf being quickly 
dried at 90° C, while the remaining leaf halves were chloroformed 
and placed under favorable conditions for curing for a period of four 



STUDIES ON THE CUEING OP LEAF TOBACCO. 



37 



days before being dried in the oven. (This material served also for 
the data presented in Table VII.) The stems were also removed from 
the second lot of leaves (b) and one half of each leaf maintained in a 
bell jar at an average temperature of 12° C. (54° F.) for 48 hours, 
while the second half of each leaf was similarly treated, but at an 
average temperature of 27° C. (80° F.). These leaf halves were then 
quickly dried at 90° C. The results of these experiments are given in 
Table IX. 

Table IX. — Effect of temperature in hastening rate of curing. 



Material. 



(a) 
Leaf killed 
with alco- 
hol (1911) 
or with 
heat (1912). 



(&) 

Leaf par- 
tially cured 
at 10° to 
12° C. 



Leaf par- 
tially cured 
at 24° to 
27° C. 



1911 samples: 

Total dry weight of 6 leaves, including stems grams. 

Starch (leaf web) per cent. 

Protein nitrogen (leaf web) do. . . 

1912 samples: 

Total dry weight of 5 half leaves, without stems grams. 

Starch per cent. 

Protein nitrogen do . . . 



61.1 
28.47 
1.90 



18.7 

41.74 

1.17 



61.5 
25.17 
1.94 



18.3 
37 
1.03 



57.6 

21.33 

1.59 



17.4 
26.46 
.87 



From the above table it is seen that where the leaf was allowed to 
cure for 24 hours there was a loss of about 3.3 per cent of the starch 
content at the lower temperature and of 7.1 per cent at the higher 
temperature, while for the leaf tissue cured for 48 hours the losses 
were 4.7 per cent and 15.3 per cent, respectively. There was no 
decrease in protein in the first case at the lower temperature, but a con- 
siderable decrease at the higher temperature; and in the second case 
there was only a small decrease at the lower temperature, but the 
decrease at the higher temperature was very marked. It is evident 
that the rate of curing is proportional to the temperature, which is in 
accord with the well-known principle that normal respiration, as 
measured by the rate of evolution of carbon dioxid, increases regu- 
larly with rise in temperature; and it is interesting to note that in 
tobacco curing the rate of increase in the speed of the reactions in- 
volved tends to obey the law of Van't Hoff that the speed of ordinary 
chemical reactions is approximately doubled for each increase of 10 
degrees centigrade in temperature, provided, of course, that in this 
case the optimum temperature for the enzyms involved in curing is 
not much exceeded. 



EFFECT OF MOISTURE ON THE RATE OF CURING. 

It is well known that the rate of drying is of fundamental import- 
ance in practical tobacco curing, and when the quantity of water in 
the leaf has been reduced to certain limits the progress of the curing 



38 



BULLETIN 79, U. S. DEPARTMENT OF AGRICULTURE. 



is practically stopped. On the other hand, if too much moisture 
remains in the leaf toward the end of the curing, when the leaf cells 
are dying, abnormal processes of decay, commonly known as pole- 
sweat, set in, which result in the disintegration of the leaf tissue. 
This latter trouble is due, however, to the invasion of foreign organ- 
isms and needs no further consideration here. Aside from these ex- 
treme conditions, we have to consider the effects of partial loss of 
water by the leaf in the course of the curing process. It is stated by 
some authorities that normal respiration is most active when the cells 
are fully turgid; that is, in the presence of a maximum amount of 
water. It appears from our experiments, however, that this prin- 
ciple does not hold so far as it relates to tobacco curing. 

In 1911 two ripe tobacco leaves were selected and the midribs re- 
moved. The two right-hand leaf halves were suspended in a tall 
closed jar for 24 hours over concentrated sulphuric acid on which 
was floated a dish containing a little caustic soda. The correspond- 
ing left-hand leaf halves were similarly placed in a jar containing 
only the caustic soda. The two lots of material were then killed 
with hot alcohol in the usual manner and prepared for analysis. The 
material which had stood over sulphuric acid was quite limp from loss 
of water, but the other sample had scarcely wilted. The leaves used 
in this experiment are comparable with those used for the 1911 
experiment shown in Table IX and therefore originally contained ap- 
proximately 28.5 per cent of starch and 1.9 per cent of protein nitro- 
gen. A similar experiment was made in 1912 with a lot of five leaves, 
the corresponding halves of which were subjected to the different 
rates of drying for 28 hours and then quickly dried at 90° C. This 
material is comparable with the 1912 samples used in the experi- 
ment presented in Table IX and therefore originally contained ap- 
proximately 42 per cent of starch and 1.2 per cent of protein nitrogen. 
The results of the tests are shown in Table X. 

Table X. — Effect of partial drying on rate of curing. 



Material. 



Leaf par- 
tially dried. 



Leaf not 
dried. 



1911 samples: 

Total dry weight of 2 leaf halves grams. . 

Starch per cent. . 

Protein nitrogen do 

1912 samples: 

Total dry weight of 5 leaf halves grams. . 

Starch per cent. . 

Protein nitrogen do — 



8.7 
12.61 
1.49 

19.05 

30.76 

1.13 



8.7 

18.27 

1.56 

19.75 

34.55 

1.10 



The final dry weight of the two 1911 samples was the same, but as 
there was a marked difference in starch content at the end of the 
experiment it is evident that the leaf halves subjected to partial 
drying were originally somewhat heavier than those not subjected to 



STUDIES ON THE CURING OP LEAF TOBACCO. 39 

drying. It is seen that initial partial drying materially hastens the 
disappearance of starch, but for the interval of time covered by the 
experiments there was no important difference in the rate of hydrol- 
ysis of protein. The less-marked differences as regards starch in 
the 1912 experiment were doubtless due to the fact that there was 
much less difference in water content (about 8 per cent) between the 
two samples as a result of the partial drying than was the case with 
the 1911 samples. In view of these results it appears that the 
thorough wilting of the tobacco leaves at the beginning of the curing 
process promotes good curing. 

SUMMARY. 

Curing is essentially a life process, as is shown by the fact that 
killing the protoplasm at excessively low or high temperatures or by 
means of poisons, such as chloroform, effectually prevents normal 
curing. It follows, also, that imperfect curing can not be fully cor- 
rected in the subsequent process of fermentation, which is not 
dependent on the living protoplasm. 

Experiments covering a period of four years have shown that in 
the case of cigar-wrapper-leaf types the average loss in weight of dry 
matter in curing the picked leaves is 12 to 15 per cent, while in curing 
the leaves on the stalk the loss in dry weight is approximately twice 
as great. In other words, a cigar-wrapper leaf picked from the stalk 
will weigh after curing approximately 14 to 18 per cent more than 
would the same leaf when cured on the stalk. 

In the curing of the export and manufacturing types and of cigar- 
filler types, which are harvested in a riper or more mature condi- 
tion, the loss in weight of dry matter is greater than in the case of 
cigar-wrapper leaf, frequently amounting to 35 to 40 per cent, even 
when the leaves are picked from the stalk in harvesting. With most 
of the export and manufacturing types the stalks are split in har- 
vesting, and under these conditions the loss in dry matter in curing 
is considerably less than when the stalk is simply severed near the 
base in harvesting. 

The chemical changes which take place in curing can only be 
properly brought out by presenting all results on the basis of the 
uncured leaf. It has been shown that in thorough air curing all 
starch and reducing sugars disappear and there is a decrease of 
pentosans and malic acid, while there is an increase in citric acid 
and the cellulose content remains unchanged. There is a large 
decrease in protein, in some cases amounting to 60 per cent of the 
total, and a considerable decrease in nicotine and total nitrogen. 
Appreciable quantities of ammonia are formed in the process. 

In the curing of picked leaves the chemical changes appear to be 
due almost wholly to respiration, while in curing the leaves on the 
stalk the phenomenon of translocation from the leaf into the stalk 



40 BULLETIN" *79, U. S. DEPARTMENT OF AGRICULTURE. 

plays an important r61e. This translocation, which constitutes the 
essential physiological difference in the two methods of curing, 
involves the transfer into the stalk of the amid and amido com- 
pounds derived from the protein, ammonia and a portion of the 
mineral constituents, nitrate and, doubtless, a portion of the carbo- 
hydrates. The picked leaves after curing contain, therefore, much 
larger quantities of amid and amido compounds, and ammonia and 
somewhat larger quantities of mineral matter and nitrate than the 
leaves cured on the stalk. 

The physiological processes characteristic of tobacco curing indi- 
cate the presence of diastatic, proteolytic, and deamidizing enzyms, 
and probably also of oxidases. The process of starvation to which 
the leaves are subjected leads to an increased secretion of diastase 
during the progress of the curing. 

Temperature has a very marked effect on the rate of curing. The 
rate of curing increases very rapidly with rise in temperature up to 
the killing point of the protoplasm (about 130° F.). The moderate 
use of artificial heat in air curing does not materially affect the final 
result in curing so far as measured by the ordinary methods of 
chemical analysis, provided other conditions remain favorable in 
both cases. 

Thorough wilting in the initial stages of the curing promotes the 
progress of the process, provided the further drying of the leaf is not 
allowed to proceed too rapidly. 

o 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914 




BULLETIN OF THE 



No. 80 




Contribution from the Forest Service, Henry S. Graves, Forester. 
August 31, 1914. 

(PROFESSIONAL PAPER.) 

EFFECTS OF VARYING CERTAIN COOKING CONDI- 
TIONS IN PRODUCING SODA PULP FROM ASPEN. 

By Henry E. Surface, 
Engineer in Forest Products, Forest Products Laboratory. 

PURPOSE OF EXPERIMENTS. 

At the present time practically all of the soft, easy-bleaching pulps 
used for the manufacture of high-class book, magazine, general print- 
ing, and the cheaper writing papers are made by the soda process. 
In England such pulps are produced from esparto (alfa, or Spanish 
grass) ; in America, from the poplars and similar woods. Although 
the soda process of wood-pulp manufacture is not employed commer- 
cially to so great an extent in America as the sulphite and mechan- 
ical processes, it is remarkably well adapted for producing pulp fibers 
from any kind of wood or other fibrous vegetable material, no matter 
how resistant to chemical attack it may be. For this reason it is 
much used in the experimental work of the Forest Service. 

To insure that a wood has been subjected to the most favorable 
cooking conditions it is necessary to cook it under many different 
conditions produced by varying such factors as the amount and con- 
centration of the cooking chemical and the duration and temperature 
of cooking. While the general effect of using greater or less severity 
of cooking is well recognized in mill practice, there has been almost 
no available information on the quantitative effects of the individual 
factors concerned nor on the limitations within which such effects 
are exerted. Such meager information as may be found in the litera- 
ture is widely scattered and is not strictly applicable to manufactur- 
ing conditions. Notwithstanding modern improvements and the 
general tendency toward more efficient operations in commercial 
plants, the most economical production apparently is not being 
attained by all of the soda-pulp mills. This is indicated by the fact 
that some of them are using from 10 to 20 per cent more pulp wood, 
from 50 to 100 per cent more chemicals, and from 10 to 40 per cent 

1 This paper presents detailed information of value in experimental work in the laboratory and in pro- 
moting the efficiency of commercial paper-making plants employing the soda process. 

31091°— Bull. 80—14 -1 



2 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

more steam, and require much larger plants and more labor for the 
same tonnage output per day than others making similar products. 
It was to secure and make available detailed information which would 
both facilitate other experimental work in the laboratory and promote 
the efficiency of commercial plants employing the soda process that 
the series of tests discussed in this bulletin was undertaken. They 
were carried out at the Forest Products Laboratory maintained by 
the Forest Service at Madison, Wis., in cooperation with the Univer- 
sity of Wisconsin. • 

The report of the experimental work is prefaced by a short descrip- 
tion of the soda process and a review of previous investigations. 
Some general comments on aspen as a raw material for soda pulp and 
on the pulp itself will be found in the appendix, pages 41-47. This 
species of poplar was selected as the test material because it is the 
most important soda pulpwood. The information secured, however, 
is of much value also in connection with the cooking of other woods. 

THE SODA PROCESS AND ITS APPLICATION. 

"What is here referred to as the soda process may be considered as 
a modification of the old Watt and Burgess process, first practiced 
in 1853/ and probably the oldest commercial method for producing 
chemical pulp from wood. It originally consisted in digesting suit- 
ably prepared wood in a large boiler with a strong solution of caustic 
soda under a pressure of about 90 pounds per square inch for 10 or 
12 hours. The wood was then washed to remove the alkali and 
treated with chlorine gas or an oxygenous compound of chlorine. 
The partially digested wood was then washed to free it from the 
hydrochloric acid formed and again treated with a small quantity 
of caustic soda solution. The pulp so produced was then washed, 
bleached, and beaten in a beating engine, after which it was ready 
for the paper machine. The modification of this process as employed 
at the present time in the United States dispenses with the interme- 
diate digestion treatment with chlorine compounds. Different cook- 
ing conditions also are used, the details of which, together with a 
brief description of the manner of preparing the wood, are given 
below. 

PREPARATION OF THE WOOD. 

While a few mills cook their wood unbarked or only partly barked, 
the general practice is to remove even the live inner bark. 2 The 

i Charles Watt and Hugh Burgess secured a United States patent on this process in 1854. It was devel. 
oped further and modified by Juillon in France (1855), by Houghton in England (1857), and by Albert 
Ungerer, to whom a British patent was issued (1872). Further modifications gradually resulted from its 
commercial application. 

2 The barking loss amounts to about one-fifth of the weight of unbarked logs. The losses in the case of 
logs from 31 trees used in these experiments varied from 16 to 20 per cent, which checks quite well with 
Ziegelmeyer's figure of 19.5 per cent on European aspen. (See Stevens, Paper Mill Chemist, p. 150, 190.8.) 
Aside from the convenience and ease of barking in the woods, the saving of freight is considerable when the 
wood is transported to the mills by railroad, and since the barked wood dries out rapidly an additional 
advantage is secured by the loss of weight in seasoning. A cord ol green aspen (about 50 per cent water) 
weighs about 1,900 pounds more than the same wood, air dry (about 15 percent water). 



PKODUCING SODA PULP FKOM ASPEN. 3 

barked or peeled wood is then cut diagonally with the grain into 
slices or chips about one-half to three-fourths inch thick by means 
of a machine called a " chipper." These pieces are then further 
broken up by means of a disintegrator, or " shredder," and the 
resulting chips are conveyed to storage bins, usually above the 
digesters. An intermediate screening operation to remove dust 
and dirt and to secure uniform chips is sometimes given them. 

On account of the strong solvent power of the cooking liquors used 
in the soda process it is not necessary to remove completely the knots 
or decayed portions of the wood. At some mills, however, the 
chips before being stored are sorted into different grades from which 
different qualities of pulp are produced. In the case of peeled wood, 
delivered as such to the mill, the outer shavings, if the wood is re- 
cleaned, are kept by themselves and converted into a lower-grade 
product. In some of the older mills the knots were removed from the 
peeled logs with a boring machine; and later the chips were picked 
over by hand. Such procedures, however, have now been practically 
abandoned in America. 

THE COOKING PROCEDURE. 

The digesters used in soda-pulp making are either rotary or sta- 
tionary, and may be either cylindrical or spherical in shape. The 
present tendency in new installations is towards stationary, vertical, 
cylindrical digesters heated by live steam which enters at the bottom 
of the digester in such a manner as to carry the cooking liquor through 
a pipe to the top of the vessel and spray it over the chips. This 
insures good circulation. The chips and cooking liquors are charged 
through a manhole at the top of the digester, the bottom of which is 
provided with a "blow-off" pipe and valve for discharging the pulp 
after the cooking is complete. Such digesters are from 15 to 50 feet 
high by from 4 to 9 feet in diameter. The larger sizes have been 
lately introduced; in the past the most common size held about one 
cord of wood and was 16 feet high by 5 feet in diameter. At the time 
of the 1905 census the average American digester produced about 
1 ton of pulp per cook, and the total combined capacity of the 208 
soda digesters in operation then was 222 tons of pulp per cook. 

As soon as the charging of chips and caustic soda cooking liquors 
is complete, steam is turned into the digester until a certain cooking 
pressure or temperature is reached. This temperature varies at 
different mills, but one corresponding to 110 pounds steam pres- 
sure per square inch is probably the most common at present. The 
pressure is continued from three to eight hours or more. 1 

WASHING OF PULPS AND RECOVERY OF COOKING CHEMICALS. * 

After the digestion process is completed the pulp in the digester 
is generally forced out under pressure or "blown" through a pipe 

1 The detailed cooking conditions employed at various mills are shown in the appendix, Tables 16 and 17, 



4 BULLETIN 80, U. S. DEPARTMENT OP AGRICULTURE. 

connected with the bottom of the digester into a "blowpit" or 
"balloon;" whence it is transferred to large washing pans. Here it 
is drained as free as possible from the strong spent cooking liquors, 
called "black liquors," and washed thoroughly, first with hot, weak, 
black liquors from the last washings of previous cooks, and lastly 
with fresh hot water. The first drainings and washings which con- 
tain the greater part of the alkali cooking chemicals are run to evap- 
orators, concentrated, and later calcined in furnaces. The burned ash, 
called "black ash," is leached with water, and the alkali in the form 
of sodium carbonate is dissolved. The resulting solution is treated 
with* quicklime (CaO), which changes the carbonate into caustic soda. 
Modern practice recovers from 88 to 92 per cent of the alkali charged 
into the digesters. By properly controlling the strength of the black 
ash solution and mixing various strengths of recausticized solutions, 
a caustic soda liquor of the desired strength for cooking is prepared. 1 

TREATMENTS GIVEN THE SODA PULP. 

After the pulp has been thoroughly washed it is diluted with a large 
amount of water and screened to remove uncooked portions. This 
is accomplished by either flat plate, diaphragm screens, or by such 
screens in conjunction with centrifugal ones. In the case of aspen 
or poplar the greater proportion of the water in the pulp is then 
removed by means of "slushers," "feltless wet machines," or 
"deckers." The pulp is then treated in a suitable vessel with bleach- 
ing-powder solution and afterwards thoroughly washed. Very little 
aspen or poplar pulp is left in the unbleached state, but is usually 
bleached immediately after it is screened. Those mills making both 
pulp and paper generally carry the bleached wet pulp directly 
through the subsequent paper-making operations; but if the pulp 
is to be sold or stored it is simply run over a paper machine into rolls 
of dry pulp (about 10 per cent water). 

PREVIOUS INVESTIGATIONS. 

The treatises by Cross and Bevan 2 and by Schwalbe 3 and the 
recent experiments 4 by Viewig, Miller-Moskan, Miller, Schwalbe, and 
Schwalbe and Robinoff give much information on the nature of the 
chemical reactions which take place between caustic soda and cellu- 
lose under various conditions, and on the formation of decomposition, 
mercerization, and other similar products from cellulose. • 

1 A few mills still cling to the older practice of not recovering the alkali from the black liquors. Such mills 
buy the alkali for cooking in the form of caustic soda (NaOH). The cooking solution is produced by dis- 
solving in water a sufficient quantity of the caustic to give a solution of the desired strength. The black 
liquors are run to waste, and, although the consumption of cooking chemicals is very high, the mills seem 
to operate at a profit. 

2 Cellulose, 1903. Also Researches on Cellulose, 1895-1900; 1900-1905; 1905-1910. 

* Die Chemie der Cellulose. 1910-1912. 

* For specific literature references see bibliography in appendix. 



PRODUCING SODA PULP FROM ASPEN. 5 

While the manufacturer of paper pulp is interested in these chemical 
investigations they do not give him much practical information on the 
interrelation of the various cooking conditions which he employs and 
the effect of their modifications on the yield and quality of the pulp. 

An article published by Tauss 1 in 1889, dealing with the effects of 
water alone on cellulose-containing materials, is of interest in connec- 
tion with the Forest Service tests because the "yield" or residue with 
zero caustic soda assists in determining the curve for the effect of 
amount of caustic soda on the yield of crude pulp (fig. 4). Tauss's 
experiments showed (Table 1) that a very appreciable amount of 
solids can be extracted from wood and from cellulose by boiling in 
water, especially at high pressures. In 1890 the same author 2 pub- 
lished the results of investigations in which caustic-soda solutions were 
employed in the place of water alone. The experiments with caustic 
soda were made partly with solutions of a concentration employed in 
commercial practice, partly with more concentrated, and partly with 
more dilute solutions. 3 The calculated residues (Table 1) afford some 
interesting comparisons with the Forest Service yield data. 

In 1907 De Cew 4 published a technical article dealing with the func- 
tion of the soda process in the production of wood cellulose. Although 
no data are cited to substantiate his conclusions, he makes the fol- 
lowing statements : 

The results obtained with, this process depend very largely upon the accuracy with 
which it is carried out. The action of caustic soda is one of hydrolysis, in which the 
woody molecule is gradually broken down with the formation of acid products which 
combine with and neutralize the alkali, leaving the cellulose in the form of isolated 
fibers. Now, if sufficient alkali were used and the cooking action continued, the entire 
fiber would finally be dissolved, although the more resistant celluloses would be the 
last to disappear. It is, therefore, necessary in order to bring into solution only the 
lignified portion of the wood to add just sufficient alkali for this purpose. 

This is almost entirely neutralized by the acid products formed from the lignocellu- 
lose, and thus very little free alkali is left in the liquor to attack the rest of the fiber, 
which should be almost pure cellulose. At first the alkali is very active and a rapid 
combination takes place, but the rate of reaction becomes continually slower as the 
free alkali grows less and the resistance increases. There are also such varying con- 
ditions as to causticity, pressure, circulation, and time of cooking, which are of con- 
siderable importance in the process, for some makers are obtaining from 1-200 pounds 
of fiber per cord more than others in treating the same kind of wood. 

i Dingl. Polyt. J., pp. 27&-285, vol. 273, 1889; Jour. Soc. Chem. Ind., p. 913, vol. 8, 1889. 

2 Ibid., pp. 411-428, vol. 276, 1890; Jr. Soc. Chem. Ind., p. 883, vol. 9, 1890. 

s See footnote, p. 16. 

* Jour. Soc. Chem. Ind., pp. 561-363, vol. 26, 1907; Chemical Abstracts, p. 319, 1908. 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



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Producing soda pulp from aspen. 7 

In regard to the time required for cooking there is a wide difference' in practice. 
However, the most improved plants are now able to effect the complete resolution of 
the wood in a very short time. In fact, any of the deciduous woods can now be 
reduced in about four hours. With the improvements in the methods of cooking that 
have been developed, which enable us to get about twice the work out of a digester 
that was formerly obtained, a number of special advantages have been found to be the 
result of these quick cooks. The shorter the time the alkali is in contact with the 
cellulose, the higher is the yield obtained and the sounder and stronger is the fiber. 
If all of the cellulose is freed from the lignin at practically the same time, the free 
alkali will have very little time to react on the weaker celluloses and the fibers will not 
be broken nor the points and serrations dissolved. Moreover, the fibers from the short 
cook are not hard to bleach, because the character of the cellulose is uniform. Under 
conditions of complete saturation with the right proportion of alkali, the lignocellu- 
loses can be almost instantly dissolved by subjecting the material to the temperature 
and pressure that is ordinarily used for cooking the fiber. The writer has performed 
this experiment on a laboratory scale, and the fiber obtained so closely resembled the 
actual structure of the woody cell that hardly any cellulose could have been dis- 
solved. 

Clapperton, 1 in 1907, in writing about the soda process, says: 

It is the necessity for employing such high temperatures and pressures (90 pounds 
per square inch) that constitutes the serious drawback to the alkali process as under 
the conditions of boiling the strong caustic soda acts on the cellulose, impairing the 
strength and reducing the yield. 2 The reason why such conditions are necessary is 
that the soluble acid bodies resolved by the caustic become so oxidized and con- 
densed that they counteract and weaken the reducing action of the soda, and in order 
to equalize their resistance higher temperatures and pressures have to be employed. 

Beveridge 3 recently published the results of some of his experi- 
ments on the effects of varying the cooking conditions in the produc- 
tion of esparto pulp. He says: 

The treatment of esparto by the soda method is typical of the preparation of paper 
pulp from nearly all fiber-yielding plants, such as bamboo, straw, wood, etc. The 
isolation of cellulose is brought about by digesting the prepared plant in an alkaline 
solution, having for its base caustic soda, at variable temperatures and under variable 
lengths of time. The chemical reaction which takes place during this digesting proc- 
ess is not known; that is to say, has not been isolated because of the complicated char- 
acter of the encrusting substances surrounding the fiber in the plant. The caustic 
soda in aqueous solution forms soluble compounds with these encrusting bodies and 
dissolves any silica which forms a part of the plant's structure, so that by subsequent 
draining, washing, and bleaching the liberated cellulose is obtained in a compara- 
tively pure state. Cellulose from whatever source it is obtained is, however, soluble 
in aqueous solutions of caustic soda. Moreover, the solvent action of the caustic is 
accelerated by heat and by the length of time (within limits) in which the two bodies 
are heated together. It is therefore apparent that if the maximum yield of cellulose 
is desired when using this method due regard must be paid to the laws regulating the 
yield. These laws may be expressed thus: The yield of cellulose obtained from any 
plant by the caustic-soda method depends upon: 

(1) The proportion of caustic soda (NaOH) used per unit weight of plant; 

(2) The temperature employed; and 

(3) The length of time the digesting operation is continued. 

i Practical Papermaking, p. 33, 2d ed., 1907. 

2 In modern commercial practice even higher temperatures and pressures are employed, and the results 
of the Forest Service tests do not corroborate Clapperton's statements as to the undesirable effects from using 
them. 

» Papermaker's Pocketbook, p. 72, 2d ed., 1911. See also Sindall, Manufacture of Paper, p. 77, 1908. 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



If any one of these conditions be altered and the other two kept constant, the yield 
varies inversely as the altered condition. Thus, in the case of esparto, the author 
performed a series of experiments in which the proportion of caustic to unit weight of 
esparto was varied, whilst the temperature and duration of time of digesting were both 
kept constant with the following results (Table 2). 

Table 2. — Experiments regarding yield of air-dry bleached palp from Oran esparto. 



No. of ex- 
periment. 


Esparto, 
weight 
taken. 


Soda liquor. 


Conditions of boiling. 


Weight of 
air-drv 
pulp: 


Dry pulp 
on dry" 
esparto. 


Bleaching 
powder. 


Volume. 


Na 2 0. 


Time. 


Tempera- 
ture. 


Pressure. 


1 


Grams. 
200 
200 
200 


Cc. . 
800 
800 
800 


Per cent. 
1.58 
2.13 

2.69 


Hours. 
3 
3 
3 


"C. 

142 
142 
142 


Lbs. 

55 
55 
55 


Grams. 
87.30 
80.67 
72.00 


Per cent. 
43.91 
40.55 
36.20 


Per cent. 
29.5 


2 


18.5 


3 


10.5 











Variable. 
Pressure varied. 
Strength of caustic varied. 
Time varied. 



Note. — The different trials were made in wrought-iron tubes fitted with screw caps, all three being 
heated together in an oil bath for three hours at a temperature of 302° F. (55 pounds above atmosphere). 

The following is taken direct from Cross, Bevan, and Sindall's 1 
resume of Beveridge's experimental results, which include the data 
quoted in Table 2 and others: 

He made three sets of trials, as follows: 
Constant conditions. 

1. Time and strength of caustic. 

2. Pressure and time. 

3. Pressure and strength of caustic. 
The results were: 

1. Increase of pressure resulted in a diminution of yield, the quantity of pulp 
obtained being reduced considerably. 

2. Excess of caustic soda caused rapid diminution in the yield of cellulose. 

3. Gradual exhaustion of the caustic soda by prolonged digestion prevented such 
serious diminution of yield. 

The discussions and experimental results which have been quoted 
show in a general way the effects of varying some of the fundamental 
cooking conditions in the soda process. None of the experiments 
cited are directly comparable to commercial practice in this country, 
because the testing conditions were not sufficiently representative of 
manufacturing conditions, and, in the case of Beveridge's experi- 
ments, because esparto — a grass, or pectocellulose — was used as the 
test material. Moreover, the effects of the cooking conditions 
employed were not studied in as great detail as seemed desirable. 
The experiments show very clearly, however, that improper cooking 
conditions are wasteful or inefficient, and indicate the need for com- 
plete experimental data on which improvements in commercial 
practice may be based. 

i Wood Pulp and Its Usea, p. 132, 1911. 



PRODUCING SODA PULP FROM ASPEN. 9 

METHOD OF CONDUCTING EXPERIMENTS. 

SCOPE AND PLAN OF TESTS. 

Aside from the character of a wood or other material prepared for 
cooking, the principal cooking conditions affecting yields and proper- 
ties of pulps, consumption of cooking chemicals, and the general 
efficiency and costs of the cooking operations are indicated under 
the following general headings : 

(1) Preliminary treatments which may in some cases be given the prepared 

chips. This includes such treatments as preliminary pressure, vacuum, or 
steaming. 

(2) Character of the cooking apparatus, including size, shape, and construction 

of the digester; manner of heating, whether by saturated or superheated 
steam turned directly into the digester, or by the use of steam jackets or 
flue gases; also the degree and kind of mechanical agitation employed, 
if any. 

(3) Proportions of the charges. This covers the amounts of wood and chemicals; 

also the amounts of water present in the wood and the original cooking solu- 
tions together with the water condensing in the charges from steam used in 
- cooking. 

(4) Character of the cooking liquors when charged. Such items as causticity, 

initial temperature, impurities, and concentration are important. 

(5) Duration of the cooking treatment. The treatment is in three periods — (a) a 

period of increasing temperature; (b) a period at maximum temperature; 
and (c) in some cases, a period of decreasing temperature. 

(6) Pressures and temperatures. This considers the pressures and temperatures 

of the digester contents at different stages of cooking; also the tempera- 
ture of the digester room (as affecting radiation and condensation). 

(7) Manner of admitting steam, "relieving," and "blowing" the digester. 

Since the effects of the variable cooking conditions may be modi- 
fied by the treatments given the pulps after leaving the digester — 
such as leaching or washing, screening and bleaching — these treat- 
ments must also be taken into account, for it is not possible to de- 
termine all the important effects of the cooking treatments until the 
finished pulps have been prepared. 

The many factors are more or less interdependent, and any change 
in one results in unavoidable changes in others. Four of the more 
fundamental of these factors have been investigated in the Forest 
Service experiments. They are: 

(1) Amount of caustic soda charged per pound of wood. 

(2) Duration of cooking at maximum temperature. 

(3) Maximum temperature (pressure) of cooking. 

(4) Initial concentration of the cooking chemicals. 

The effect of these four factors upon the yield and properties of the 
pulp and the consumption of cooking chemicals were determined. 1 

1 The purely chemical aspect of the cooking action has not been given special consideration. The effect 
of the caustic soda cooking liquors under the conditions employed in pulp making is recognized as a hydro- 
lytic action in which the caustic soda extends the limits of hydrolysis. This subject has been given care- 
ful attention by Cross and Bevan, Schwalbe, De Cew, and others as indicated in previous references. The 
effects of the cooking conditions on the recovery of soda also have been given no consideration except in a 
very cursory manner. The laboratory facilities did not permit this important subject to be studied at the 
time of the experiments. 



10 



BULLETIN" 80, U. S. DEPARTMENT OF AGRICULTURE. 



The tests fall naturally into four groups; in each group all the condi- 
tions were held as nearly constant as possible except the factor under 
investigation, which was varied in successive tests or "cooks" accord- 
ing to a definite plan. The plan of the tests is shown in Table 3. In 
addition to the factors mentioned in this table all other factors under 
control were so far as possible held constant. Those for which values 
were specified are the following: 

Amount of chips for each charge, 40 pounds bone-dry weight. 

Dryness of chips, air dry. 

Causticity of cooking liquors, 95-98 per cent. 

Temperature of charging cooking liquor, 22° C. (72° F.) 

Temperature of digester room, 22° C. (72° F.) 

Duration of cooking before maximum pressure is reached, 1 hour. 

Duration of cooling and relieving digester before blowing, 5-10 minutes. 

Blowing pressure, 30 pounds per square inch. 

Table 3. — Plan of cooking experiments. 





Num- 
ber of 
tests. 


Cooking conditions under investigation. 


Test 
group. 


Initial concentration 
of caustic soda in 
digester liquors. 1 


Amount of caustic 
soda per 100 
pounds of wood. 1 


Maximum cooking 
temperature 
(equivalent steam 
pressure). 


Duration of cooking 
at maximum pres- 
sure or tempera- 
ture. 


I. 

II. 

III. 


6 
6 

6 

4 


Constant — SO grams 
per liter. 

Same as Group I 

do 


Variable — from 15 
to 40 pounds in 
steps of 5 pounds 
each. 

Constant— 25 pounds 
(value selected 
from Group I tests 
as most satisfac- 
tory for later tests). 

Same as Group II . . . 

do 


Constant — 100 
pounds per square 
inch. 

Same as Group I 

Variable— from 70 to 
120 pounds per 
square inch in 
steps of 10 pounds 
each. 

Con stan t—1 
pounds per square 
inch (value se- 
lected from Group 
III tests as most 
satisfactory for 
later tests). 


Constant— 6 hours. 

Variable — from 1 to 
11 hours in steps 
of 2 hours each. 


IV. 


Variable— from 110 

to 50 grams per 
liter in steps of 20 
grams each. 


(value selected 
from Group II tests 
as most satisfac- 
tory for later tests). 
Same as Group III. 







iln commercial practice it is customary to vary the amount of chemical used and its initial concentra- 
tion both at the same time when attempting to change the severity of the cooking due to these factors. 
This results in the volume of the cooking liquors being kept approximately the same, which is a desirable 
feature. In these tests, however, it was the intention to find out the effects of each factor separately. 

TESTING PROCEDURE. 

The apparatus employed in cooking is shown in figure 1. Figure 
2 shows diagrammatically the course of the material through the 
various stages of treatment and testing, and in this way the relation 
of one part of the procedure to another is made clear. 

After the amount of moisture in the chips had been ascertained 
by means of sample A, the charge was weighed out and put into the 
digester. Caustic soda solution, of the desired concentration and 
volume, had been prepared by diluting the necessary Quantity of 
analyzed stock solution (sample B) with water. It was then heated 



PRODUCING SODA PULP FROM ASPEN". 



11 



to the charging temperature and run into the digester, and the cook- 
ing operation was begun by permitting live steam to enter at the 
bottom. 

During the cooking, observations were made at 15-minute intervals 
of (1) digester temperature, (2) digester pressure, (.3) steam pressure 
at digester inlet, and (4) room temperature. The volume of liquor 




in the digester was also observed, but at hourly intervals. These 
observations were recorded, and a graphic "log of cook" was made 
at the same time, an example of which is shown in figure 3. If at 
any time the digester temperatures and pressures as observed on the 
thermometer and pressure gauge did not agree when compared by 
means of pressure-temperature tables for saturated steam, the excess 
of pressure was relieved ; such a condition occurred as a rule only dur- 



12 



BULLETIN 80, U. S. DEPARTMENT OP AGRICULTURE. 



ing the first hour of cooking. The room temperature and the pres- 
sure of steam at digester inlet were kept as near constant as possible 
for all the tests, so that all conditions affecting condensation, aside 
from the cooking operation itself, would be uniform. For the same 

| STEAM MAINl I ALKALI STORAGE TANK~| | STORAGE CANS~] | WATER MAIN 1 



CAUSTIC SODA LIQUOR 



STEAM SEPARATOR | 



WATER 



CHIPS 



SAMPLE A 



1 LIQUOR PREHEATER 

CAUSTIC SODA AND WATER 



SCALES I 

CHIP CHARGE 



DIGESTER 



RELIEF LIQUOR 



BLOW PIT 



'AMI' 



BLACK LIQUOR 



BLACK LIQUOR 



| BLACK LIQUOR TANK 



PRESS 



LEACHEJp 



BLACK LIQUOR 



DRAWINGS 




PRESSED PULP 

1 SHREDDER 1 

SHREDDED PULP 
f SCALES 
SHREDDED PULP 



SAMPLE D 



BEATER 
T 



CRUDE PULP AND WATER 

CENTRIFUGAL PUMP 

CRUDE PULP AND WATER 

STOCK TANK 

CRUDE PULp! AND WATER 



SCREEN 



SCREENINGS AND WATER SCREENED PUL P AND WATER 

WATER EXTRACTOR | | WATER EXTRACTOR 



SCREENINGS 

| SCALES 

SCREENINGS 



WATER WATER 



SAMPLE E 



WASTE 



SEWER 




PULP AND WATER 

STUFF CHEST" 
1 

PULP AND WATER 

| MACHINE SCREEN 1 

PULP AND WATER DIRT AND SCREENING* 



PAPER MACHINE 



WASTE 



WATER 



DRY PULP IN ROLLS 
UNBLEACHED 




Fig. 2.— Flow sheet, showing course of material through the various stages of treatment and testing. 

reason, steam of approximately the same moisture content was used 
in all tests. 

During the first hour of cooking the digester pressure and tempera- 
ture were brought, at a uniform rate, up to the maximum to be 



PEODUCING SODA PULP FEOM ASPEN". 



13 



employed, and were held constant at this value during the remainder 
of the cook. At the end of the cooking period the top relief vent 
was opened and the digester pressure quickly "relieved" until 
"blowing pressure" was reached, when the vent was closed, the two 
blow-off valves were opened, and the digester was emptied under 
blowing pressure with 
the assistance of a steam 
ejector in the blow-off 
line. 

The pulp was caught 
in the blow pit, where 
it was washed with three 
or more 50-gallon appli- 
cations of hot water. 
After the blowing and 
after each successive 
washing the pulp was 
allowed to drain, and the 
drainings were pumped 
to the black-liquor stor- 
age tank. The washing 
operations were contin- 
ued until the last drain- 
ings were of a specific 
gravity lower than 1 .003 
at 22° C. Inasmuch as 
the top relief pipe emp- 
tied into the blow pit, it 
was possible to collect 
the small amount of 
relief liquors, together 
with the black liquors, 
in the storage tank, 
where the volume of the 
whole was read off on 
the graduated tank 
gauge ." A sample of this 



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Fig. 3.— Typical graphic log of cook. (Cook 24.) 

(sample C) was secured for analysis, and the amount and character 
of the recovered chemicals determined. (Fig. 2.) 

After the last washing the crude pulp in the blow pit was drained 
as dry as possible and, by means of scoops, removed to a strong linen 
bag inclosed in a perforated metal cylinder. The pulp in this form 
was then placed under a 70-ton, knuckle-joint, power press. After 
being pressed to about 30 per cent bone dry the pulp was next 



14 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

"opened up'' in a swing-hammer shredder running at low speed 
and without a cage, so that the largest lumps after shredding were 
about hazelnut size. This was done to facilitate sampling and 
increase the accuracy- of the dry-weight determinations. The 
shredded pulp was weighed and sampled (sample D) for determin- 
ing the dry weight. It was then mixed with water and further 
opened up in a 25-pound Hollander-style beater, with the roll well 
off the bedplate so that no real beating could take place, and was 
pumped from the beater to a 200-gallon stock tank at the head of the 
screening system, where it was diluted with water to a known volume. 
This mixture was then screened by means of a 6-plate diaphragm 
screen with slots 0.009 inch wide. The screenings which went over 
the plates were then collected, weighed, and sampled (sample E), as 
described for the crude pulp. The screened, unbleached pulp which 
went through the screen slots, mixed with a large amount of water, 
was run to a water extractor and concentrated. Afterwards it was 
pumped to the paper machine stuff chest, made up to a known volume 
with water, pumped to the machine screen (diaphragm type, 0.012 inch 
slots), and run out on a 15-inch Fourdrinier paper machine (see PL I), 
into a sheet 10 inches wide by about 0.010-0.011 inch thick. The 
rolls of the screened, unbleached pulp thus secured were stored await- 
ing the tests to determine its properties for winch samples G to R 
were taken. Where the screenings were so large in amount as to 
preclude accuracy of sampling the crude unscreened pulp, such pulp 
was screened without the preliminary pressing, shredding, etc., and 
the screened pulp was collected on a 70-mesh sieve, pressed, shredded, 
weighed, and sampled for the yield determinations. The pulp was 
then screened again and made up into a sheet as described. 

The methods used for determining dry weights, yields, quality 
of pulps, and composition of liquors are given in the appendix. 

TEST MATERIALS USED. 

WOOD. 

The test material consisted of 3 1 logs of aspen (Populus tremuloides, 
Michx.) cut from representative trees growing intermixed with 
wliite birch near Rhinelander, Wis. The trees were of seed growth 
and had attained an average height of 44 feet, with straight, clear 
lengths of about 22 feet from which the logs were cut. 

The ages of the logs varied from 28 to 42 years, as determined by 
counting the annual rings. The logs were fairly free from knots, 
considering the size of the trees and the species. Volume-weight 
determinations on 36 samples, representative of the whole shipment, 
showed the average bone-dry weight per cubic foot of green or 



PRODUCING SODA PULP FROM ASPEN. 15 

unseasoned wood free from knots to be 26.68 pounds. The samples 
ranged from 23.6 to 31.4 pounds per cubic foot. 

As a rule the test material was sound, but some of the logs had 
decayed hearts. The material was peeled by means of a carpenter's 
drawknife; all decayed portions on the outside of the pieces and all 
protruding knots were chopped off. Tins cleaned wood was then 
sawed into disks five-eighths inch thick in the direction of the grain. 
Butts, tops, and all disks containing decay or other defects were 
culled. 

The remaining sound disks were split with the grain into chips 
1 inch to 6 inches by one-fourth inch by means of a special guillo- 
tine chipping machine. All knots were culled. The chips were 
then seasoned to constant air-dry weight, thoroughly mixed and 
screened to remove sawdust and dirt, and finally stored in cans to 
await the cooking tests. 

COOKING CHEMICALS AND SOLUTIONS. 

In ordinary mill practice the soda cooking liquors are made as 
described on page 4. The freshly causticized solution contains 
caustic soda (NaOH) for the most part, but a small amount of soda 
ash (sodium carbonate, Na 2 C0 3 ) still remains uncausticized. Various 
impurities are also present, but these are considered to have no 
effect in cooking. 

In the experiments the cooking solutions were made by dissolving 
fused caustic soda, 76 per cent * sodium oxide (Na 2 0), in water. 
The resulting solution was similar to the solutions used in commer- 
cial practice so far as caustic soda and soda ash are concerned, and 
there is no reason to believe that the results should be different in 
any way from those which would have been obtained by the use of 
commercial liquors of the same concentration and causticity. 

EFFECTS OF VARIATIONS IN THE COOKING CONDITIONS. 

The influence of the variable cooking condition in each group of 
tests on resultant yields and properties of pulps and consumption 
of cooking chemicals is shown graphically in figures 4 to 15. 2 The 
same results in greater detail are given in Tables 10 to 14 of the 
appendix. While, in general, the tests were carried out in accord- 
ance with the plan which has been described, minor departures could 
not be avoided, and the location of certain points on the diagrams 
are more or less affected by such variations. For this reason the 
tabulated data should be consulted for the exact conditions of each 
cook. 

1 Manufacturer's analysis. 

2 The numerals opposite each platted point on the curves are the serial numbers of the cooks. (See 
Tables 10 to 14.) 



16 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

YIELDS. 

The effects on yields of pulp and screenings are expressed by the 
curves in figure 4, in which the yields are plotted against the amount 
of caustic soda, the duration of cooking, the pressure of cooking, and 
the initial concentration of caustic soda. 



AMOUNT OF CAUSTIC SODA. 



With increases hi the amount of caustic soda per pound of wood 
the yield of total crude pulp decreased at the rate of about 1 per 
cent for each 2 per cent of caustic (0.02 pound NaOH per pound of 



3 60 

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0URATI0N AT MAX. PRESSURE-HOURS 



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60 70 80 90 100 110 120 
MAX. PRESSURE-PDS. PER SO. IN. 



40 50 60 70 80 90 100 110 
CONCENTRATION NaOH-GRAMS PER LITER 



O -TOTAL CRUDE PULP 



• -JCMHED1MUACHED PULP 



F IG- 4.— Effects of cooking conditions on yields of total crude pulp, screened unbleached pulp, and 

screenings. 

wood). The yield at zero caustic soda would probably fall between 
80 and 90 per cent, being influenced only by the cooking effect 1 of 
the water condensed from the steam used in cooking. For high 
amounts of caustic soda the curve tends to approach parallelism 
with the horizontal axis. The yield would not be expected to become 
zero unless exceeding^ large amounts of caustic were used. 2 

For amounts of caustic soda above what may be considered the 
minimum for successful cooking under the conditions used, the yield 

1 See Tauss's experiments, Table 1. 

' Tauss used for a single boiling as high as 7 pounds of caustic soda per pound of wood, and the yield 
or undissolved material after three hours at 58.8 pounds per square inch steam pressure amounted to 8.52 
per cent for beech and 2.87 per cent for pine. With 4 pounds caustic soda per pound of wood in each of 
three successive three-hour treatments under a steam pressure of 132.3 pounds per square inch, the yields 
for the two woods were 20-61 per cent and 18.20 per cent, respectively. This latter proportion of caustic 
soda was ten or more times as great as is ordinarily employed in commercial practice. Also tho other 
cooking conditions wcro proportionately more severe. 



Bui. 80, U. S. Dept. of Agriculture. 



Plate I. 




PBODUCIJSTG SODA PULP FROM ASPEN". 17 

of screened unbleached pulp was identical with that of crude pulp, 
but for smaller amounts of chemical it rapidly approached zero, 
while under the same conditions the screenings curve naturally 
approaches and becomes coincident with the curve for the total 
crude pulp. In this group of tests the minimum amount of caustic 
soda for successful cooking, so far as yields alone are concerned, is 
somewhere between 15 and 20 per cent. 

DURATION OF COOKING. 

The duration of cooking at maximum pressure influenced the 
yields in very much the same manner as did the amount of chemical. 
The yield of total crude pulp decreased about 1 per cent for each 
additional hour of cooking at maximum pressure. However, the 
curve (fig. 4) seems to approach parallelism with the horizontal axis, 
thus signifying that beyond a certain point cooking would have had 
no further effect. 1 The time allowed for these cooks to reach the 
maximum pressure was one hour, and the extended curve indicates 
a yield of about 60 per cent for zero hours duration at maximum 
pressure. This shows that the greater part of the cooking was 
accomplished during the first hour, or before the maximum pressure 
was attained, since during that hour about 40 per cent of the wood 
substance had been dissolved and the dissolving effect during the 
next 12 hours was only one-fourth as great. 

As determined by the yield curves, the minimum duration for 
successful cooking under the conditions employed was between one 
and three hours at maximum pressure. No tests were made between 
these two points. 

PRESSURE OP COOKING. 

The curve showing the influence of maximum cooking pressure or 
temperature on yields indicates that all of the tests were made at 
pressures above the minimum required for successful cooking, under 
the conditions employed for these tests; hence, no screenings were 
obtained from any of the cooks, and the curve for screened unbleached 
pulp coincides with that for total crude pulp. Increases of pressure 
from 70 to 120 pounds per square inch resulted in decreasing the 
yields of pulp about 1 per cent for each five pounds, which indicates 
that the higher pressures increase the thoroughness of cooking, other 
conditions being constant. 

CONCENTRATION OF CAUSTIC SODA. 

The tests varying the initial concentration of caustic soda in the 
digester liquors were also made within limits that resulted in thorough 
cooking for all of the tests. Increasing the concentration under the 

1 Figures 12 and 13 show that the active cooking chemical was consumed at the end of 7 hours at maxi- 
mum pressure; it is therefore not apparent from these tests what would be the effect of continued cooking 
in the' presence of available -caustic soda. 

31091°— Bull. -80—14 2 



18 



BULLETIN 80, IT. S. DEPARTMENT OF AGRICULTURE. 



WO 



50 



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a 


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?i 


i 


s . 










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.10 



■20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 



100 



50 



100 



TR 



JiSU-jS 



2 4 6 8 10 12 

DURATION AT MAX. PRESSURE-HOURS 



conditions employed resulted in decreasing the yields of pulp about 
1 per cent for each 13 grams per liter increase in concentration. It 
is thus evident that with a given amount of chemical the greater 
cooking effect is secured by means of the more concentrated solutions. 
A practical limit of course exists at the point where the volume of 
the digester liquor becomes too small to afford favorable cooking 
conditions. 1 

PROPERTIES OF UNBLEACHED PULPS. 

NATURAL COLOR. 

Curves indicating the effects of the conditions of cooking on the 
natural color of the unbleached pulps are shown in figure 5. 

The larger the amount of 

caustic soda used per pound 
of wood the lighter in color 
was the pulp, as indicated by 
the "parts black" color rat- 
ing, but the curve approaches 
parallelism with the horizontal 
axis as the amounts of caustic 
increase. White pulps or those 
with zero " parts black" would 
not be obtained even if exceed- 
ingly large amounts of chemi- 
cal were used. 

Longer periods of cooking 
produced lighter-colored pulps 
up to the point where the 
maximum yield of screened 
pulp was obtahied. Beyond 
this point there was a tendency 
for the pulp to become slightly 
darker as the duration of cook- 
ing was increased. This was probably due to the pulp fibers absorbing 
and retaining coloring matters from the "black liquors." It is gen- 
erally believed that as the cooking becomes more thorough the 
cellulose of the fibers gradually becomes more gelatinous or hydrated, 
and would therefore tend to retain coloring matter during the subse- 
quent leaching and washing treatments. 

The pressure (temperature) of cooking seems to have had compar- 
atively little effect on the color of the pulp within the range investi- 
gated. 

1 As the initial concentrations increased, the volumes of digester liquors at the start of cook decreased 
(see fig. 17), since the amount of caustic soda was held constant. Hence, increasing concentrations would 
eventually result in a volume of digester liquor so small that the whole charge of chips would not be covered 
until late in the cooking period after the liquor had been sufficiently diluted by the condensed steam used 
in cooking. In this case part of the chips would receive very severe treatment, while the remainder would 
more or less escape the cooking effect. The resulting pulp would represent a composite of the two con- 
ditions. 



« 50 



-2°U 



60 



i 



70 80 90 100 110 120 
MAX. PRESSURE-PDS. PER SQ. IN. 



100 



50 



__, 


1 






S* 






<— 




2 


as' 




r *** 



40 50 60 70 80 90 100 110 
CONCENTRATION NaOH -GRAMS PER LITER 

Fig. 5.— Effects of cooking conditions on the color 
("parts black") of pulp. 



PRODUCING SODA PULP FROM ASPEN. 



19 



The more thorough cooking resulting from the higher initial con- 
centrations of caustic soda produced lighter-colored pulps, although 
the lower limit of {he cooking condition in these tests was considerably 
above the minimum for successful cooking. 

While the several curves shown in figure 5 indicate for each group 
of tests more or less change in the " parts black" color ratings or the 
depth of color, the hues of the 
pulps were not materially- 
affected. 



1000 



OCCURRENCE OF SHIVES. 

Shives are most numerous 
in pulps from the less severe 
cooks and are entirely absent 
from those thoroughly cooked. 
The shives curves (fig. 6) bear 
some resemblance to those for 
the yields of screenings, but 
shives disappear from the pulps 
only under somewhat more 
severe cooking conditions than 
those which reduced the yield 
of screenings to zero. At the 
point of maximum yield of 
screened pulp the cooking has 
progressed far enough for the 
fibers to become more or less 
separated from each other, but 
not completely so, since some 
of them still remain in groups 
(shives) small enough to pass 
the screen slots. But as the 
cooking becomes more severe 
the fibers are entirely sepa- 
rated, and the resulting pulp 
is free from shives. In gen- 
eral, increasing the amount of 
temperature of cooking, or the 
liquor decreases the "shiviness" 



800 



600 



400 



.200 



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POUNDS NaOH PER POUND OF WOOD 



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400 

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DURATION AT MAX. PRESSURE-HOURS 




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70 80 80 100 110 120 
• MAX. PRESSURE- PDS. PER SQ.IN. 




Fig. 6.- 



50 60 70 80 90 100 110 
CONCENTRATION NaOH-GRAMS PER LITER 

-Effects of cooking conditions on the occur- 
rence of shives in pulp. 



caustic soda, the duration or the 
initial concentration of the digester 
of the pulp. 



ASH CONTENT. 

The curves in figure 7 indicate that increasing the thoroughness 
of cooking within certain limits decreases the ash content of the pulp; 
outside of these limits the ash content may be increased. 
• Since the normal amount of ash in aspen wood is not over three- 
quarters of 1 per cent, the high amounts in the pulps produced 



20 



BULLETIN 



U. S. DEPARTMENT OP AGRICULTURE. 



from this wood in some of the tests is probably due to the presence 
of cooking chemicals * which were not completely removed during the 
washing treatments. Increasing amounts of ash as the cooking 
conditions become more severe may be due to a difference in the 
physical character of the cellulose produced under such conditions 
and the resultant mcreased difficulty of leaching out and washing 
away any residual and absorbed mineral matters. No tests were 
2JD made to determine the char- 
acter of the ash from any of the 



1.5 



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STRENGTH. 



.10 



.20 .30 .40 

POUNDS HaOH PER POUND OF WOOD 



2.0 



° 1.0 



1.0 



0.5 



1.0 













,0 . 






tf s 






13 












^K 


14 




• 
12 









2 4 6 8 10 12 
DURATION AT MAX. PRESSURE- HOURS 



0.5 



2? 


2I< 


'—is 


L-j^ 










18 


17 







60 



The strength of a pulp de- 
pends chiefly upon three fac- 
tors — (1) the strength of the 
individual fibers ; (2) the felting 
or matting quality of the fibers ; 
and (3) the presence of gelatin- 
ized fibers and other matters 
which act as cementing ma- 
terials. 

Severity of cooking is at- 
tended by a weakening of the 
cell walls and may result in a 
decrease in the strength of the 
pulp. This decrease of strength 
was strongly marked in the tests 
in which the more severe cook- 
ing conditions were produced 
by increasing the amount of 
caustic soda. It was most rapid 
up to the point where the fibers 
were completely separated (indicated by the absence of shives), be- 
yond which it was less pronounced. For increasing durations of 
cooking the general trend 2 of the effect was the same as for 
increasing amounts of chemical, but the total decrease in strength 
was not quite so great in amount for the range of cooking conditions 
investigated. 



70 80 90 100 110 120 
MAX. PRESSURE PDS. PER SQ.IN. 



2?' 




25 




« 
















23 



ft- 1.0 



o.s 

40 50 60 70 80 90 100 110 
CONCENTRATION NaOH -GRAMS PER LITER 

Fig. 7.— Effects of cooking conditions on the ash 
content of pulp. 



1 Special precautions were taken, to eliminato the influence of dirt. Further it does not seem reason- 
able that the cooking action which removed the lignin and other organic matters should have produced in 
the fibrous residue or pulp a concentration of the mineral constituents which go to form the wood ash. 

2 The data are not sufficient for expressing the effect in detail. The true curve would be expected to 
have a bend coinciding with the point of maximum yield of screened pulp or the point where the shives 
are reduced to zero. 



PRODUCING SODA PULP FROM ASPEN. 



21 



Increasing the pressure and increasing the initial concentration 
beyond a certain point both increased the strength of the pulp. 
This effect is apparently contradictory to that found for the other 
two groups of tests and may possibly be due to the high tempera- 
tures and high concentrations which would tend to cause a physical 
change in the cellulose with in- 
crease of the cementing effect 
mentioned previously. 

Curves showing the influence 
of cooking conditions on the 
strength of pulp are given in 
figure 8. 



3.5 



- 3.0 



2.5 



(A 2.0 



1.5 





8 














\ 1 






















7*-~-~ 




£ 


& 
















~4* 







.10 



.20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 



i 3.b 

1 30 
d 

at 

W 2 5 


















I6~~ 




14 


^13 


« 








W 

B 

c 2.0 


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15 








10 







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DURATION AT MAX. PRESSURE-HOURS 



3.5 



3.0 



X 2.5 



a- 2.0 











i 


>y 


'IT 






22 






liS 










\2 




20 











60 



70 80 SO 100 110 120 
MAX. PRESSURE-PDS. PER SQ.IH. 



EASE OP BLEACHING. 

The chief purposes of bleach- 
ing are (1) to produce a white 
pulp and (2) to destroy any non- 
cellulose materials which tend 
to make the pulp less durable. 
The more nearly the original 
pulp approaches to pure cellu- 
lose the less is bleaching re- 
quired. However, difficulty of 
bleaching is occasioned not only 
by the presence of ligneous mat- 
ters, but also by coloring mat- 
ters absorbed in the cell walls 
from the "black liquors" and 
by the residual cooking chem- 
icals which the leaching and 
washing treatments have failed 
to remove. In the latter case 
a certain amount of bleach is 
neutralized by reactions with 
the other chemicals. 

Curves expressing the effects 
of varying the cooking condi- 
tions on the ease of bleaching, as measured by the amount of bleach 
required to bring the pulps to a standard white color, are shown in 
figure 9. These curves show that under the conditions of cooking the 
residual ligneous matters are the most important factor in determin- 
ing the amount of bleach required, since the more thorough cooking pro- 
duces pulps that are more easily bleached. The decrease in amount of 



3.5 



S 3.0 



£ 2.5 



°- 2.0 

40 50 60 70 30 90 100 110 
CONCENTRATION NaOH -GRAMS PER LITER 

Fig. 8. — Effects of cooking conditions on the strength 
of pulp. 















J 


L 












s 


/ 






26 




25 




24 







22 



BULLETIN 



U. S. DEPARTMENT OF AGRICULTURE. 



bleach required was very rapid up to the point where shives were 
eliminated; beyond this point the effect was less marked. It must 
not be assumed, however, that the shives alone necessitated the larger 
amounts of bleach. The presence of shives indicates an incomplete 
cooking reaction and implies that considerable ligneous matter may 
remain in the other (completely separated) fibers. 

The effect of severity of the 
cooking conditions is especially 
noticeable in the curves for the 
tests varying the amount of 
caustic soda and the duration 
of cooking, since certain of the 
pulps produced in these tests 
were less thoroughly cooked 
than any of those from the 
other groups. 



30 



20 



10 



s 



.20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 



30 



a: 20 



10 



Vis 


















V is 


«^»* 


13 


12 


















10 







LOSS ON BLEACHING. 



2 4 6 8 10 12 

DURATION AT MAX. PRESSURE-HOURS 



se 20 





[22 


21 


20 


















19 ' 


1 ' 







60 



70 80 90 100 110 120 
MAX. PRESSURE-PDS. PER SO.. IN. 



to 



The curves showing the 
losses on bleaching as affected 
by the varying cooking condi- 
tions are given in figure 10. 
As would be expected, the loss 
decreased with thoroughness 
of cooking. In the tests vary- 
ing the amounts of chemical 
and the durations of cooking 
the rate of decrease in bleach- 
ing loss with greater severity 
of cooking was fairly constant, 
but it is probable that if the 
cooking conditions were ex- 
tended for higher values than 
those used the curves would 
approach parallelism "with the horizontal axis. Such an effect was 
obtained for the tests in which the cooking pressures were varied. 
It is not reasonable to believe that more severe cooking would result 
in pulps which would suffer no loss whatever on bleaching. 

The platted points for the tests in which the initial concentrations 
were varied are so few in number and so irregular in location that 
they give little indication of the influence of this factor. However, 
additional information is obtained from some earlier tests of the Forest 
Service, summarized in Table 4. 



o 

40 





26 




















>-5 ' 




'ST" 


1 


23 



50 60 70 80 90 100 110 
CONCENTRATION NaQH-GRAMS PER LITER 



Fig. 9. — Effects of cooking conditions on the ease of 
bleaching. 



PRODUCING SODA PULP FROM ASPEN. 23 

Table 4. — Effect of concentration on bleaching losses (autoclave tests). 1 



Cook 
No. 


Concentra- 
tion of 
NaOH. 


Yield of 

total crude 

pulp. 


Yield of 
screenings. 


Bleach 
required. 


Loss on 
bleaching. 


1 
2 
4 


Grams per 
liter. 
80 
50 
30 


Per cent. 
41.10 
44.23 
46.97 


Per cent. 

0.10 

.03 

.07 


Per cent. 
15.4 
14.7 
15.8 


Per cent. 
3.92 
4.08 
4.68 




.20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 



i Each cook employed seven hours' duration at 110 pounds pressure per square inch. The caustic soda 
charged amounted to 0.25 pound per pound of wood. For complete information see appendix, Table 15. 

These data indicate that increasing the concentration reduces the 
loss en bleaching, hence the curve in figure 10 has been drawn to show 
such an effect. This is sub- 
stantiated by the fact that 
varying the amount of chemi- 
cal and the duration and pres- 
sure of cooking in each case 
showed a reduction in the 
bleaching losses as the severity 
of cooking increased, and that 
most of the other curves for 
the effect of concentration 
(especially the yield, shives, 
and bleach-required curves) 
show more severe cooking with 
the higher concentrations. 

The relatively large amount 
of loss in the case of cook 23 
does not seem to be warranted 
in view of the well-cooked con- 
dition of the pulp. However, 
the comparatively high strength 
of the pulp indicates an abnor- 
mal condition. 

The loss in weight of a pulp 
during bleaching is due prima- 
rily to the removal of the col- 
ored ligneous matters and to 
the partial destruction of the 
cellulose itself. The latter is 
especially liable to occur if the 
bleaching treatments are severe, or if the cooking treatments have left 
the cellulose in an easily oxidized condition, so that it is either dis- 




2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 



\ 


c 
















s 

2i 


>- 


< 


'" < 


l" . 


17 




i 


|20 









60 



70 80 90 100 110 120 
MAX.PRESSURE-PDS.PER SQ.IN. 







( 


, 25 






< 


21 


i 

26 


r 






i 


'24 







40 



SO 60 70 80 90 100 110 
CONCENTRATION NaOH-GRAMS PER LITER 

-Effects of cooking conditions on the bleach- 
ing loss. 



24 



BULLETIN" 80, U. S. DEPARTMENT OF AGRICULTURE. 



solved during bleaching or broken up into small particles, which are 
removed in the washing operations. The partial removal of the min- 
eral or ash-forming constituents from the pulp may also occasion some 
loss. On the other hand, the ash in bleached pulp sometimes tends 
to hicrease over that for the unbleached pulp (due to an accumulation 
of lime compounds and other residues from the bleaching solution), 
and hence may offset the loss due to other causes. 

RELATION BETWEEN PROPERTIES AND YIELDS. 

Many of the curves expressing the effects of the varying cookino- 
conditions on the properties of the unbleached pulps have bends or 

30 































1 




TEST VARYING 

o AMOUNT OF CAUSTIC SODA 
ODURATION OF COOKING 
•PRESSURE OF COOKING 
« CONCENTRATION OF CAUSTIC SODA 
©PRELIMINARY TEST 














































1 
















\ 




















































































o 
























































3?f 


^ • 




















a 


9 




09 














o 








a 


< 


) 

















































44 46 48 50 52 54 56 58 

YIELD-TOTAL CRUDE PULP -PER CENT 

Fig. 11. — Relation between yields and ease of bleaching. 

"breaks" at or near the values for the cooking conditions which 
resulted in the highest yields of screened pulp. So general is this 
that, with decreasing severity of cooking, the occurrence of sudden 
changes of direction for curves expressing properties affords a reliable 
indication that the yield of screened unbleached pulp is near its maxi- 
mum. This is especially evident in the curves for ease of bleaching. 
That properties of pulps are directly dependent upon yields is well 
illustrated when amounts of bleach required are platted against yields 
of total crude pulp, as in figure 11. Values for all of the cooks made 
in these experiments have been platted, irrespective of the testing 



PRODUCING SODA PULP FROM ASPEN. 25 

conditions under which they were secured; It is evident that cooks 
which resulted in decreased yields produced easier bleaching pulps. 
For the higher values slight differences in yields are accompanied by 
marked differences in the ease of bleaching, but the effect rapidly 
diminishes until a large decrease in the yields affords little difference 
in the amounts of bleach required. This would be expected in view 
of the nature of the cooking reactions. The effect is first to remove 
the intercellular substances and part of the ligneous matters from the 
wood, then the cellulose itself begins to be attacked, and finally, after 
the greater part of ligneous matters has been removed, the cellulose 
alone is affected. The ease of bleaching is a measure of the amount 
of noncellulose matters present in the pulp. 

Other properties of the pulps when similarly platted against yields 
show more or less definite relationships, but are apt to be modified 
according to the cooking condition varied. For instance, when vary- 
ing the amount of caustic soda or the duration of cooking, decreased 
yields were attended by decreased strength of pulp ; when initial con- 
centrations or pressures were varied, the strength increased as the 
yields decreased. Natural color, shives, and screenings, however, 
were little affected for yields below 54 per cent, no matter how pro- 
duced; for higher yields the color, shives, and screenings increased 
rapidly with increasing yields. The losses on bleaching followed 
fairly closely the amounts of bleach required, and hence decreased as 
the yields decreased. 

SIGNIFICANCE OF PROPERTIES. 

There are at present no accepted standards of quality or market 
grades of soda pulps. What may be sufficiently good quality for one 
purpose or one mill may be poor or medium quality for another. 
Aside from bulkiness and opacity, which depend mainly on condi- 
tions not studied in these experiments, the desirable properties of a 
pulp are, in general, as follows: 

(1) Low percentage of bleach, required. 

(2) Low loss on bleaching. 

(3) High strength. 

(4) Durability (resistance to wear and decomposition). 

(5) Low ash content. 

(6) Few shives. 

(7) Absence of dirt. 

(8) Light color for the unbleached pulp. 

(9) Whiteness of the bleached pulp with freedom from certain undesirable tints. 

It is not often that any one pulp has the advantage over another in 
all of these properties, and for many uses some of them are of no 
importance. For aspen (poplar) or other short-fibered pulps used in 
the manufacture of book papers the properties which are given most 



26 



BULLETIN 80, IT. S. DEPARTMENT OF AGRICULTURE. 



consideration are freedom from dirt and strives and low percentage of 
bleach required, with the attendant low loss on bleaching. Both 
undercooked and overcooked pulps are to be avoided. 



CONSUMPTION OF CAUSTIC SODA. 



By consumption of caustic soda is meant the neutralization of the 
free or active caustic soda (NaOH) existing as such in the digesting 

liquors. The neutralization re- 



WOr^: 



90 



80 



70 



K)0 



90 



80 



70 



100 



90 



80 



? 


















1 


1 ^ 


1 


16 

























.20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 









^£- 


k 


% 








/i 5 


' *I4 












Y 

















2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 



suits from the combination of 
the sodium (Na) of the alkali 
with the acid products derived 
from, the hydrolysis of the 
lignified fibers during cooking. 1 
The black liquors at the end 
of the cooking treatments con- 
tain in dissolved form these 
nonalkaline, sodium com- 
pounds, together with the re- 
maining free caustic soda. 

The effects of varying the 
cooking conditions on the con- 
sumption of caustic soda, ex- 
pressed in per cent of the 
amount charged or the effi- 
ciency in its use, are shown in 
figure 12. The actual con- 
sumption in pounds per 100 
pounds of wood is shown in 
figure 13. 

As would naturally be ex- 
pected, the greatest compara- 
tive efficiency for the cooks 
made with varying quantities 
of caustic soda resulted from 
the use of the smaller amounts. 
However, when very small 
amounts were employed, the 
cooking reactions were not sufficiently complete, 2 as indicated by the 
curves for yields and properties of the pulps. In this group of tests 
well-cooked pulps were first obtained with about 0.2 pound of NaOH 
per pound of wood. The efficiency in the use of the caustic at this 
point was about 85 per cent. 

i See De Cew's discussion, p. 0. 

2 It is a well-known chemical law that in order to carry a reaction to a given degreeof completion for one 
of the reacting substances it is necessary to have available a certain excess of the other chemical or chemicals 
which take part in the reaction. This means that the efficiency in the use of the chemical can not be 100 
per cent. The speed of the reaction is proportional to the amount of the excess. 



^ 70 











( 


!3-— i 


17 










/^l 


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< 


Pa 


,21 


'20 











60 



70 80 90 100 110 120 
MAX.PRESSURE-PDS.PER SO.. IN. 



100 



90 



80 





28 


















« 


sr— 




24 


1 


23 

■— — - 



40 



SO 60 70 80 90 100 110 
CONCENTRATION NaOH -GRAMS PER LITER 



Fig 



12. — Effects of cooking conditions or 
ciency in the use of caustic soda. 



the efli- 



PRODUCING SODA PULP FROM ASPEN. 



27 



40 



30 



20 






.10 



.20 .30 40 
POUNDS NaOH PER POUND OF WOOD 



30 



u. 20 





IS 


14 


•' 3 


,« 


•" 














— •« 

















2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 



With increasing durations of cooking the efficiency in the use of 
caustic soda increased until it reached a constant maximum value. 
An efficiency of 95 per cent was obtained by seven hours' cooking at 
maximum pressure, and, since no greater efficiency was secured by 
continuing the cooking four additional hours, it is apparent that this 
represents the maximum efficiency attainable. That the cooking 
reactions are not due entirely to the presence of active caustic soda 
is indicated by the fact that after the 95 per cent efficiency had been 
attained increased durations resulted in some further cooking effect 1 
(see curves for yields and prop- 
erties of pulps) with no increase 
in the amount of chemical con- 
sumed. Increasing the pres- 
sure also resulted in greater 
efficiency in the use of caustic 
soda until a maximum of 95 
per cent was obtained. 

In all groups of tests in which 
a constant amount of caustic 
soda was charged into the di- 
gester for each cook, greater 
percentage efficiency in its use 
could mean only a greater 
actual consumption of the 
chemical. In the group of 
tests varying the amounts of 
caustic soda, the decrease in 
percentage efficiency was ac- 
companied also by increase in 
the actual consumption. It is 
thus apparent that the more 
thorough cooking, whether 
produced by increasing the 
amount of chemical in the 
charge or the duration or the 
pressure of cooking, is, in large part at least, due to the greater com- 
pleteness of the reaction between the chemical and the wood. 

The tests employing various initial concentrations of caustic soda 
in the digester liquors (the amount of caustic soda charged remaining 
the same) seemingly do not bear out this conclusion. In most 
respects the determinations of yields and properties of the pulps in 
these tests indicated that the more concentrated solutions resulted 
in more thorough cooking, but no increase in the consumption of 
chemical occurred; in fact, with increase of concentration, a decrease 




60 



70 80 90 UO 110 120 
MAX. PRESSURE-POS. PER SOUIN. 




50 60 70 80 
CONCENTRATION NaOH- 



90 100 HO 
GRAMS PER LITER 



Fig. 13.- 



-Effects of cooking conditions on the amount 
of caustic soda consumed. 



1 For the effect of water alone, see Tauss's experiments, Table 1. 



28 



BULLETIN 



U. S. DEPARTMENT OF AGRICULTURE. 



of consumption and subsequently decrease of percentage efficiency 
are indicated. While the possibility of error is not ehniinated, 1 this 
result indicates the need for further investigation. 

RELATION" BETWEEN" CAUSTIC SODA CONSUMED AND YIELDS. 

For the purpose of further studying the cooking effects of the 
various conditions employed, yields of total crude pulps from all of 
the cooks were platted against amounts of caustic soda consumed 
per 100 pounds of wood charged (fig. 14). The average curve drawn 
through these points indicates a definite relation between yields and 



84 
80 

£ 76 

UJ 

u 

25 72 

OL 
1 

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3 

a. 
S 64 

cr 

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I- 

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£ 52 




































TEST VARYING 

©CONCENTRATION OF CAUSTIC SODA 
OAM0UNT OF CAUSTIC SODA 
ODURATI0N OF COOKING 
^PRESSURE OF COOKING 
©PRELIMINARY TEST 






































































o > 




€> 
























o ^s 


o 


o 




3 




















1 




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^0 










44 































10 12 14 16 18 20 22 24 26 28 30 32 34 
NaOH CONSUMED PER 100 PDS.0F BONE DRY W00D-PDS. 

Tig. 14.— Relation between yields and amount of caustic soda consumed. 

amounts of caustic soda consumed, regardless of the cooking condi- 
tions. However, even if it is assumed that the location of some of the 
points is due to experimental errors, the relation, as regards individual 
cooks, can be only an approximate one, since it has already been 
pointed out that in some of the tests increased cooking effects were 
obtained without any increase in the consumption of caustic soda. 
If the curve were produced for lower amounts of caustic soda, the 
yields would probably be somewhere between 80 and 100 per cent 
at zero consumption, since under these conditions cooking could still 
be effected by water alone. 2 

I The test data show a loss of digester liquor overflowing through the "top relief" for cooks 25 and 26 
(that for cook 26 showing the greatest loss), and it is due to the platted points for these two cooks that the 
curves indicate greater consumption of caustic soda at the lower concentrations. 

5 See Tauss's experiments, Table 1. 



PRODUCING SODA PULP FROM ASPEN. 29 

Since the completion of these experiments Mr. E. Sutermeister has 
published 1 the results of some tests in which a small rotary autoclave 
and copper flasks were used as cooking vessels. Yields varying from 
93 to 24 per cent and consumptions of caustic soda varying from 
to 29 pounds per 100 pounds of wood were obtained, 2 giving a relation 
similar to that indicated by the curve in figure 14. However, in his 
experiments a greater reduction of yields was obtained per unit 
decrease in the caustic soda consumed, which is probably due to 
differences in test material, method of experimentation, and appa- 
ratus employed. 

The actual consumption of caustic soda during cooking is a factor 
which is not given sufficient consideration in commercial practice, 
although it is one of considerable importance for an intelligent control 
of the cooking operations. By a careful study of the consumption, 
together with the other effects of the various cooking conditions, it is 
possible to determine the best operating conditions. That pulp 
mills do not ordinarily determine the consumption of caustic soda and 
the efficiency of its use is due to the length of time necessary for the 
analysis of the black liquors. While the method used in these experi- 
ments requires some time for carrying out the analysis, its occasional 
use in commercial operations would be of benefit in determining the 
conditions to be used in future cooks. 3 If there were a rapid and 
accurate method of analysis such as is used in sulphite mill operations, 
it would assist in determining when the cooking had progressed far 
enough, at which time the digester could be blown. Production of 
undercooked or overcooked pulps would thus be avoided. 

SEVERITY OF COOKING AS INDICATED BY MICROSCOPIC APPEARANCE OF FIBERS. 

A good indication of the thoroughness or severity of cooking may 
be obtained by microscopic examinations of the pulp fibers. 4 The 
effects of varying the cooking conditions are shown in figure 15; 
curve A represents the relative abundance of vessels in the pulps; 
curve B, the ray cells; curve C, the fiber bundles or shives; curve D, 
the prominence of the vessel markings; and curve E, the apparent 
strength of fiber walls. Since there are no absolute units for measur- 
ing these effects, the ordinates as shown for each curve represent 
arbitrary units ranging from to 10. The photomicrographs in 
Plates II to VII, inclusive, present some of the more pronounced 

i Paper, p. 15, No. 2, vol. 9, Sept. 25, 1912. 

2 In obtaining yields higher than 75 per cent the test material was treated at atmospheric pressure. Under 
this condition the cooking effect of water alone would have but little influence unless long durations of 
treatment were used. 

3 The boiling of rags with caustic-soda solutions for the production of rag pulps is controlled in this manner. 
* For the normal appearance of fibers in the uncooked wood see Plates VIII and IX, as well as the discus- 
sion on p. 42. 



30 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



effects. 1 While various gradations resulted, 2 the experimental pulps 
may be classified in the following three groups: 

Overcooked pulps. — Severe digestion treatments resulted in "over- 
cooked" pulps, examples of which are seen in Plates II and III. 
The walls of the fibers show a considerable degree of weakness, 
as indicated by their thin transparent appearance and by tbeir 
much twisted and fractured condition. The relative number of 
vessels present in the pulp is low as compared with the normal 
number present in the wood, and the pits and other markings on 
them are only dimly visible. Many of the vessels remaining are 



COOK MO. 


| J 


» i 


6 5 4 


A 
















B 


1 


^ 


^ 
















f i 


r — 


C 




N 


<v 










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^« — i 












E 

















1 — i 

A 


i 1 


*— — 1 


1 1 


1 1 


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B ' 














1 


C ' 


s 


1 — 1 


1 H 


> 1 


>— 1 


1— — 


I 


— i 



1 J 


*— — 1 


1 1 


1 1 


» « 


I 




E 

















jO 4 20 .30 .40 
* POUNDS NaOH PER POUND OF WOOD 



60 70 80 90 100 110 120 
MAX. PRESSURE- PDS. PER SO. IN. 




A 




























B 




























C 


















D 






























1 


>— 


E 


— ( 


> 


1 


> 1 











2 4 6 8 10 12 

DURATION AT MAX. PRESSURE- HOURS 



40 50 SO 70 80 90 100 110 
CONCENTRATION NaOH- GRAMS PER LITER 



Fig. 15.— Effects of cooking conditions on pulp fibers. A, abundance of wood vessels; B, ray cells; 
C, fiber bundles, or shives; D, prominence of vessel markings; and E, apparent strength of fiber 
walls. 

ragged and partly disintegrated; and the pulp, for the most part, 
is also characterized by an absence of the comparatively thin-walled, 
delicate ray cells. Fiber bundles abo are absent, since these are 
made up of fibers bound together by groups of the brick-shaped ray 
or parenchyma cell. The indistinctness of the vessels and fibers is 
due chiefly to the removal of the ligneous infiltrations of the cell 
walls, in consequence of which the elements developed very little 
color from the particular stain used in making the microscopic 
mounts. 

Well-cooked pulps. — Pulps produced under less severe conditions 
are made up of stronger fibers, such as shown in Plates IV and V. 

1 The remarks following the title of each plate and the discussion in the text are not based on the fields 
shown in the photomicrographs alone. 

2 The photomicrographs, in the order of their sequence, show gradations of severity of cooking. 



PRODUCING SODA PULP FROM ASPEN". 31 

The milder treatments are apparent in the increasing number of 
ray cells and vessels, the latter being well preserved and showing 
their markings quite clearly. The fibers are twisted or broken to only 
a small extent, and yet are so well separated that there are no fiber 
bundles. 

Undercooked pulps. — Plates VI and VII illustrate the character- 
istics of undercooked pulps, and show plainly the mildness of the 
digestion treatments employed in their production. Well-preserved 
vessels with sharply defined markings are clearly visible, ray cells 
are numerous, and the walls of the fibers are less dissolved away 
than in the more thoroughly cooked pulps. Coincident with these 
characteristics there are also present many fiber bundles or shives> 
noticeable even when the microscopic slides are examined with the 
naked eye. Undercooked fibers develop a deep color from the particu- 
lar stain used in mounting, and on this account appear very distinct. 

Of the several groups of tests, the one varying the amounts of 
caustic soda per pound of wood resulted in the greatest range of 
severity of cooking as determined by the microscopic appearance 
of the pulp fibers. A small amount of chemical resulted in an under- 
cooked pulp. With increases in the amount the strength of cell 
walls gradually decreased, the wood vessels suffered gradual destruc- 
tion, and their markings were dimmed. The ray cells and fiber 
bundles disappeared soon after the point was reached where the 
maximum yield was attained. The higher amounts of caustic gave 
the overcooked effects. 

For varying durations of cooking the effect was practically the 
same, and undercooked pulps were obtained at the shortest duration 
used. However, the highest durations employed did not give as 
severely cooked pulps as were obtained with large amounts of chem- 
ical. While all of the tests varying the cooking pressures resulted in 
fairly well cooked pulps, there was a tendency toward undercooking 
at the lowest pressure used. The tests varying the initial concentra- 
tions also resulted in well-cooked pulps, except for the highest con- 
centration, where a slight overcooking effect was observed. 

INFLUENCE OF COOKING CONDITIONS ON COST. 

While it is not feasible from the data at hand to discuss all cost 
factors affecting the commercial production of pulps, the more direct 
effects of the cooking conditions employed can be shown. The actual 
effects on the cost of production, of course, depend upon various 
other operating conditions at any particular mill, but the general 
trend of the effects is the same, irrespective of local conditions. 

TIME. 

Shorter durations of cooking result in more efficient use of the 
digesting apparatus; more cooks can be made per day or per week, 



32 



BULLETIN 80, U. S. DEPARTMENT OP AGRICULTURE. 



and, as has been shown, yields of pulp per unit of wood are also 
increased, and consequently more pulp is secured per cook. The 
greater plant capacity thus obtained would result in a proportionate 
decrease of operating costs per ton of pulp. 

Figure 16 shows the production of pulp per 24 hours continuous 
operation for each 100 pounds of wood capacity of digester as influ- 
enced by various durations of cooking. The curve was derived from 
the experimental data, assuming a one-hour period for blowing the 
digester after completing a cook and for charging the next cook, and 

a similar period for 
attaining maximum 
cooking pressure. 
Thus, for a three-hour 
period at maximum 
pressure, the total 
time between the 
charging of two con- 
secutive cooks is five 
hours. Computation 
shows that decreas- 
ing the duration at 
maximum pressure 
from eight to five 
hours increases the 
daily output 48 per 
cent, while a decrease 
from ten to three 

Fig. 16. — Effect of duration of cooking on production in 24 hours. ., . . 

hours increases the 
output 156 per cent. If the time allowed for blowing and charging 
the digesters and for raising the digester pressure is decreased, the 
increase in the daily output will be even more pronounced as the 
duration of cooking is shortened. 

STEAM CONSUMPTION. 

While the consumption of steam varies with the duration of cook- 
ing, it is influenced also by the pressure maintained in the digester 
and more by the relative volumes of the liquor charge. Under the 
testing conditions employed, the volume of liquor varied both with the 
amount of caustic soda charged (the concentration being constant) 
and with the concentration (the amount of chemical being constant). 
Since the heating was accomplished by steam blown directly into the 
digester, a measure of the amount of steam used is afforded by the 
increase in the volume of liquor during cooking. 1 The effects of the 

i The steam used was not perfectly dry, containing a small amount of moisture or "priming." How- 
ever, as the steam was of approximately the same moisture content for all tests, the "condensation" was 
proportional to the amount of steam used. 







































































































250 


































































































g 


















































1 




































































































! 200 


































































































a 


































































































in 


















































j 150 


















































? 


















































b 


















































































































































* 


















































g IUU 








































































































































































































50 



















































5 6 7 8 9 10 11 
0URATI0H AT MAX PRESSURE-HOURS 



12 13 



Bui. 80, U. S. Dept. of Agriculture. 



Plate II. 










Fibers of an Over-Cooked Pulp Produced with a Large Amount of Caustic 
Soda. (Cook 4.) Magnified 65 Diameters. 

Partial disintegration has taken place. The fibers are fragmentary and contorted with rather 
weak cell walls. The vessels with barely visible markings are on the point of being 
eliminated. 



Bui. 80, U. S. Dept. of Agricultuie. 



Plate III. 




Fibers of an Over-Cooked Pulp Produced with a High Concentration of Caustic 
Soda. (Cook 23.) Magnified 65 Diameters. 

The fibers are somewhat fragmentary. 



Bui. 80, U. S. Dept. of Agriculture. 



Plate IV. 




Fibers of a Well-Cooked Pulp Produced with a Medium Amount of Caustic 
Soda. (Cook 7.) Magnified 65 Diameters. 

This is a pulp of average good quality. Vessels are well denned. 



Bui. 80, U. S. Dept. of Agriculture. 



Plate V. 



I 



'M~Ml 




Fibers of a Well-Cooked Pulp Produced with a High Pressure of Cooking. 
(Cook 17.) Magnified 65 Diameters. 

This is a strong-, well-separated pulp. 



Bui. 80, U. S. Dept of Agriculture. 



Plate VI. 




Fibers of an Under-Cooked Pulp Produced with a Short Duration of Cooking. 
(Cook 16.) Magnified 65 Diameters. 

Many shives. consisting of two or more unseparated fibers which parallel each other, are present. 



Bui. 80, U. S. Dept of Agriculture. 



Plate VII. 




Fibers of an Under-Cooked Pulp Produced with a Small Amount of Caustic 
Soda. (Cook 9.) Magnified 65 Diameters. 

Note the vessels with well-defined marking-sand the ray cells holding together a group <>f fibers 

constituting a shive. 



PRODUCING SODA PULP PROM ASPEN. 



33 



cooking conditions on the resultant condensations are shown in figure 
17. Curves showing the initial volumes of digester liquors for two 
of the groups of tests are also included in the same figure. 

In the tests employing various proportions of caustic soda, the 
amount of liquor at the start of cook varied directly with the amount 
of chemical, as shown by the straight-line curve. The condensation 
also increased rapidly as the amounts were increased. The down- 
ward turn in the heavy-line curve for the higher proportions of caustic 
is caused by the digester becoming filled and overflowing through the 
top relief during the final stages of cooking. However, the dotted 



u. . 

u- o .4 

°.a 

S3e .2 

«£ .10 



9 



.20 



.30 



.40 



si * 

dS 



28" 








|« . |[ , 








|JS 




















>2t^ 




,23 



POUNDS NaOH PER POUND OF WOOD 



u^ 40 50 60 70 80 90 K)0 110 
CONCENTRATION NaOH -GRAMS PER UTER 



:.^ "^ 



.10 .20 .30 .40 

POUNDS NaOH PER POUND OF WOOD 



C 2 4 6 8 10 12 
(JURATION AT MAX. PRESSURE- HOURS 























— 




- **! 




«,. 










26 1 






25 

















13 


•T2 


T- 


















IS 

• 


^>s 


1 »* 











2 U 

« U 
£1-2 



°- 1.0L 

a- 40 SO 60 70 80 90 100 110 

CONCENTRATION NaOH-GRAMS PER LITER 



a' 
§1.0 

« .8 

^ ■ 

'& 



















22. 


*'« 


, 20 ( 


1 '» 


18, 




T7 










< 


► 



















70 80 90 100 IK) 120 
MAX. PRESSURE -PDS. PER SO. IN. 



Fig. 17.— Effects of cooking conditions on initial volume of digester liquors and on condensation of 

steam. 

line shows the corrected curve, taking the overflow into consideration. 
The rapid increase in the condensation is a natural consequence of 
increasing the amount of cooking liquor, which has a high specific 
heat. 

In the tests employing various cooking periods the main influence 
on steam consumption was the heat lost by radiation, since the 
initial volumes of digester liquors were constant. The curve in 
figure 17 representing this effect has been drawn as a straight line 
to show only the general trend. It will be observed, however, that 
the platted points occur in two distinct groups. That the reaction 
between wood and caustic soda is of an exothermic or heat-generating 
nature may partly explain this arrangement. In the one group, 
representing the cooks of longer duration, the cooking reaction was 
31091°— Bull. 80—14 3 



34 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

practically completed before the end of the cooking period (see 
analogous curves in figs. 12 and 13). This would result in relatively 
higher amounts of condensation, since no heat of reaction would be 
generated during the later stages of cooking. 1 The same explanation 
could apply to the cooks made at the higher pressures. 

The influence of higher cooking pressures on steam consumption 
results from the greater amount of steam required to heat the digester 
and its contents to the higher temperatures and the greater loss of 
heat by radiation at such temperatures. The initial volumes of 
cooking liquor did not vary. The condensation curve indicates that 
this effect was comparatively small in the tests. 

Like the tests varying the amount of caustic soda, those varying 
the initial concentration influence the steam consumption principally 
by the amount of liquor in the charge, which varies as shown by the 
true hyperbolic curve in figure 17. Hence, increasing the initial 
concentration decreased the condensation, as shown by the corrected 
curve in figure 17, which takes into account the overflow of the 
digester in cooks 25 and 26. 

In considering these results from a commercial standpoint it should 
be kept in mind that the experimental apparatus was comparatively 
small. On this account the heat or steam required for raising the 
temperature of the digester and for replacing heat lost by radiation 
per unit of digester capacity was far greater than would be experienced 
in mill operation. Hence, much less, steam per pound of chips would 
be required in commercial operations than is shown by these curves. 
The effects of increased duration of cooking and increased pressures 
especially would be much less pronounced, since with these radiation 
is the more important factor. 

Aside from the direct cost of steam, the condensation is of impor- 
tance in another way. The tests have shown that decreased initial 
concentrations, other cooking conditions being constant, result in less 
severe cooking. It is to be expected that the decrease of concentra- 
tion throughout the cooking period, due to condensation, also tends 
to minimize the cooking effects in a similar manner. 2 

The use of superheated steam in cooking, the installation of larger 
digesters, the insulation or lagging of digesters, and the use of the 
minimum volume of cooking liquors at the start of cook are means 
frequently employed by pulp mills to reduce the condensation. 

1 The condensation curve (liauor in digester— gallons) in fig. 3, which is typical for most of the individ- 
ual cooks in these experiments, also shows a greater rate of condensation at the end of the cook than at 
earlier periods except during the first hour when the pressure was being increased. This can be accounted 
for only by the fact that heat, other than from the steam alone, was supplied to the digester during the 
earlier stages of cooking. As the cooking reaction is most vigorous at the beginning, it seems probable 
that the heat supplied was heat of reaction. 

2 It is evident that the effects obtained in the tests varying the initial concentrations are much less pro- 
nounced than would have been the case if the diluting effect of condensation had been absent. The auto- 
clave tests, for which data are given in Table 15, afford fairly conclusive proof of this. 



PRODUCING SODA PULP FROM ASPEN. 



35 



CHEMICALS PER TON OF PULP. 

The chemicals directly employed in the manufacture of soda pulp 
affect cost of production, in that the full amount of alkali charged to 
the digester can not be recovered, while the bleaching powder after 
being used is of no further value. The curves in figures 18 and 19, 
expressing the effects of the 
cooking conditions on the 
amounts of chemicals em- 
ployed per ton of air-dry, 
bleached pulp, were derived 
from the experimental data 
as explained on page 48, ap- 
pendix. The amounts shown 
are less than those generally 
employed in commercial prac- 
tice, for several reasons: (1) 
The yields of pulp are higher; 
(2) the losses on bleaching 
are less; (3) the amounts of 
chemical charged per pound 
of wood are less; and (4) the 
amounts of bleach required 
are less. Whether or not 
pulp mills can duplicate or 
approach these results, the 
general trend of the curves 
would not be affected. 



2200 



2000 



180Q 



1600 



1400 



1200 



1000 



800 



1800 



1600 



1400 



1200 



1000 













/ 
















/ 












s/s" 










































iJ 












9 


A 


>e 













.20 30 .40 

POUNDS NaOH PER POUND OF WOOD 



"\ 








,„ 


f ' 


• 




\ 
















\ 


Ns. 




13 




10 










14" 




-12* 









2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 



SODA ASH. 



1400 



© 1200 



1000 









19 


<8 ( 


Ji 




"* 


22 


2lj 


20 













60 



70 80 90 100 110 120 
MAX.PRE5SURE-PDS.PER SO.. IN. 



1300 



1100 




SO 60 70 80 90 .00 110 
CONCENTRATION NaOH- CRAMS PER LITER 



The amounts of caustic 
soda and sodium carbonate 
charged to the digester in the 
several groups of tests have 
been calculated to show the 
equivalent amounts of com- 
mercial soda ash (58 per cent 
Na 2 0) per ton of bleached 
pulp produced. (Fig. 18.) 
Increasing the amounts of 
caustic soda charged per pound of wood obviously results in increas- 
ing amounts of soda ash per ton of pulp, and the decreased yields 
of pulp resulting from the more thorough cooking make the effect 
more pronounced. A bend is found in the 'curve at the point of 
maximum yield, since for amounts of caustic below this point the 
yields decrease rapidly and their influence on the amount of soda 
ash employed per ton of pulp becomes more apparent. 



Fig. 18. — Effects of cooking conditions on amount of 
soda ash employed per ton of pulp. 



36 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



When varying the durations and the pressures of cooking and the 
initial concentrations, the amounts of soda ash per ton of pulp were 
affected by yields alone, and the mmimuni amount is employed under 
conditions which give the maximum yields. Increased durations, 

pressures, and concentrations 
afford decreased yields, and 
the amount of soda ash per 
ton of pulp consequently is 
increased. The platted point 
for cook 10 is not on the curve, 
due to the initial digester 
liquors for this cook having 
had about 3 per cent lower 
causticity than the other cooks 
in this group of tests. Lower 
causticities involve the use of 
a greater amount of soda ash 
for the same amount of caustic 
soda. 



600 



500 



a. 400 



o. 300 



uj 200 



100 



500 



400 



9 

"Ih- — ,t> s 



.20 .30 .40 
POUNDS NaOH PER POUND OF WOOD 



uj 300 



M 200 



100 



400 



a. 300 



200 



m 


































\»I5 


















14 


a 


— 21L 


to 




1 



2 4 6 8 10 12 
DURATION AT MAX. PRESSURE- HOURS 



100 



I 


c 
















V 


,*• 


















20"-~-< 


J9 


J8 


,17 





60 70 80 90 100 110 120 

MAX. PRESSURE-PDS. PER SQ. IN. 



200 



100 



40 50 60 10 80 90 100 IK) 
CONCENTRATION NaOK-GRAMS PER LITER 

Fig. 19. — Effects of cooking conditions on amount of 
bleaching powder employed per ton of pulp. 

cent available chlorine, and losses in 
are disregarded. 



BLEACHING POWDER. 

The curves in figure 19 show 
that increasing the amounts 
and concentrations of caustic 
soda and the durations and 
pressures of cooking result in 
all cases in decreasing the 
amounts of bleaching powder 
consumed. 

Yields do not influence the 
calculations, since the con- 
sumption per ton of bleached 
pulp depends on the per cent 
of bleach required and the 
bleaching losses. The ordi- 
nates for the curves represent 
bleaching powder of 35 per 
making the bleaching solutions 



COMBINED COST OF WOOD AND CHEMICALS PER TON OF PULP. 

The curves in figure 20 show costs for certain items in producing 
a ton of bleached pulp -(2,000 pounds air-dry basis) as influenced by 
variations in the cooking conditions. Curves marked A represent 
cost of wood alone; curves B, cost of wood and soda ash; and curves C, 



PRODUCING SODA PULP FROM ASPEN". 



37 



cost of wood, soda ash, and bleaching powder. The vertical distances 
between curves A and B represent cost of soda ash alone, and those 
between curves B and C represent cost of bleaching powder alone. 

The cost values were obtained by calculations from the amounts 
of wood, soda ash, and bleaching powder consumed, based on the 
experimental results. 1 A 90 per cent recovery of the cooking chem- 
icals charged to the digester was assumed in determining the amounts 



26 
24 

22 
«o 
5 20 

_i 

© 18 

o 

I ,6 

A. 14 

_l 

3 

Ik 

O 

z 10 

































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\ 














\ 












\ 




^e 




_^" 


>? 


»•* 






\ 


V 


S* 


*< 


i 


A 






V 


^^ 











.10 



.20 30 .40 

POUNDS NaOH PER POUND OF WOOD 















" 1 




















































\\ 




c 












\ 


























\ 


^ vS. 


















A 













2 4 6 8 10 12 
DURATION AT MAX. PRESSURE-HOURS 



18 

CO 

t- 

w 16 

o 
u 

14 
12 



10. 



c ■ 

"""A 



60 



TO 80 90 100 110 120 

MAX. PRESSURE -PDS. PER SQ IN. 



c 

_j_ — ~~~ — " 

a" 



40 50 60 70 80 90 100 110 

CONCENTRATION NaOH-GRAMS PER UTEJt 



Fig. 20. — Effects of cooking conditions on cost items per ton of pulp. A, wood; B, wood and soda 
ash; and C, wood, soda ash, and bleaching powder. 

of soda ash consumed or lost per ton of pulp. The basic units for 
costs are assumed average values as follows: 

Wood, $9 per solid cord (100 cu. ft.); soda ash (58 per cent Na 2 0), 
SI per 100 pounds; bleaching powder (35 per cent available chlorine), 
$1.55 per 100 pounds. 2 The bone-dry weight of aspen wood is taken 
as 26.68 pounds per cubic foot of clear wood, green volume. 

i These amounts were calculated by interpolating from the yield curves (fig. 4), the loss on bleaching 
curves (fig. 10), and thecurves for soda ash and bleaching powder employed per ton of pulp (figs. 18 and 19), 
and not from actual test data. On this account platted points have been omitted. 

2 Reasonable maximum, average, and minimum values for a "solid cord" of aspen f. o. b. mill are $11, 
$9, and $6, as determined from statistical reports received from a number of mills. Correspondence with 
pulp manufacturers brought the information that reasonable maximum, average, and minimum unit 
costs as defined above may be assumed with a fair degree of accuracy as follows: For soda ash, $1.20, $1, 
and $0.85; for bleaching powder, $2.05, $1.55, and $1.10. These values do not depend upon market fluctua- 
tions alone, but vary through the range given, due largely to differences in freight charges lor mills in 
different localities. The actual selling price of "58 per cent" soda ash is 10/48 greater than the manufac- 
turer's or market quotations, since the latter are based on the old standard of "48 per cent" soda ash. 



38 BULLETIN" 80, TJ. S. DEPARTMENT OP AGEICULTUPE. 

With increasing amounts of caustic soda in the digester charges 
the cost due to all three factors is decreased until the point of maxi- 
mum yield of good pulp is attained, after which the total costs 
increase, due to the increasing amounts of wood and of soda ash 
consumed. The decreasing cost of bleaching powder only partially 
offsets the increase due to the other two factors. 

With increasing durations the effect is practically the same, so far 
as wood alone is concerned, except that the increase in its cost for 
higher durations is not so pronounced as with increasing the amounts 
of caustic soda. The soda-ash costs alone are practically constant, 
and hence increase the wood costs by a constant amount. However, 
as the durations increase, the bleaching-powder costs decreased suffi- 
ciently to overcome the effect of increasing wood costs. After the 
minimum duration for successful cooking (as determined by yields) 
has been exceeded, the decrease hi total cost is very small, and would 
not be sufficient to offset increased costs incident to the time element 
discussed previously. 

For variations in the pressures of cooking, the influence of bleaching- 
powder costs is especially marked. The minimum costs due to wood 
and soda ash result from the use of the lower pressures. When 
bleaching is considered, the minimum cost is obtained by using 
medium pressures, although the increases for the higher pressures are 
very small. 

Combined costs for the three factors are practically unaffected by 
variations in the initial concentrations, but if bleaching is omitted the 
costs of wood and soda ash are larger with the higher concentrations. 

All of the diagrams show that of the three cost factors considered, 
wood is of the most importance and that bleaching powder is more 
influential than soda ash in determining total costs. Increases in 
costs of wood and soda ash with increasing severity of cooking are, 
in all cases, offset, to a greater or less extent, by decreases in bleaching- 
powder costs. If maximum or minimum values 1 had been used for 
either wood, soda ash, or bleaching powder, instead of the average 
value, or if a different percentage recovery for the soda ash had been 
assumed, the general effects would not be changed, although they 
might become more or less pronounced. 

SUMMARY. 2 

(1) The amount of caustic soda per pound of wood, the duration 
of cooking, the pressure or temperature of cooking, and the concen- 
tration of the cooking chemicals employed in the production of soda 

1 See footnote, p. 37. 

2 The more general statements in the summary will be found to coincide in a greater or less degree with 
previously existing opinions, a fact not surprising when it is remembered that the soda process has been 
carried on for half a century. On the other hand, satisfactory evidence and data substantiating these 
opinions have not been available. The present investigation affords such information, as well as a basis 
for more specific conclusions. 



PRODUCING SODA PULP FBOM ASPEN. 39 

pulp influence the yield and properties of the pulp by influencing the 
severity of the cooking reactions. 

(2) Severity of cooking is an effect mainly of the amount of caustic 
soda consumed per unit of wood. Increasing the amount or concen- 
tration of the chemical or the pressure of cooking produces a quicker 
reaction and hence one more complete in a given length of time. 
Increasing the duration results in a more complete reaction because 
of the longer time allowed for the available caustic soda to be con- 
sumed. 

(3) Greater severity of cooking is accompanied by a decrease in 
the yield of crude pulp, and usually of screened pulp. If screenings 
are present in considerable quantity (due to incomplete cooking), 
more thorough cooking increases the yield of screened pulp. 

(4) The properties of the pulp are influenced by greater severity 
of cooking as follows: 

(a) Shives are decreased in number or eliminated. 

(6) Bleaching is rendered more easy and the loss on bleaching becomes less. 

(c) The strength may either decrease or increase, depending upon which cooking 

condition is varied and the degree of variation. 

(d) The color of the unbleached pulp becomes lighter within certain limits, 

beyond which it may, under certain conditions, become darker. 

(5) A good indication of the severity of cooking is the appearance 
of the individual fibers when examined under the microscope. 

(6) The decreased yields resulting from more severe cooking result 
in a greater cost of wood and soda ash per ton of pulp. As a rule, 
the smaller cost of bleaching powder incident to the more easily 
bleached pulp produced by thorough cooking only partially offsets 
the greater cost of wood and soda ash. 

(7) While the amount of bleach required decreases with increasing 
severity of cooking, a point is soon reached where the decrease in 
bleach required is not commensurate with the decrease in yields. 

(8) Increasing the initial amount of digester liquor increases the 
condensation and steam consumption (and hence the cost) because 
of the greater volume to be heated; increasing either the duration 
or pressure has a similar effect because of the greater losses of heat 
by radiation. 

(9) Yields (bone-dry basis) of well-separated unbleached pulps as 
high as 56 or 58 pounds per 100 pounds of wood can be obtained from 
aspen if the wood is of the best quality. Yields of from 54 to 55 per 
cent were obtained which required only from 10 to 11 per cent of 
bleach. The variation in yields obtained by changing the cooking 
conditions was from 46 to 58 pounds per 100 pounds of wood charged, 
or about 26 per cent based on the lowest yield. 

(10) Minimum total durations of from 3 to 4 hours may be success- 
fully applied to the cooking of aspen for bleaching pulps, provided 
the other cooking conditions are properly maintained. 



40 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

(11) Aspen may be successfully cooked with a minimum of from 
20 to 25 pounds of caustic soda charged per 100 pounds of wood. 
The amount of this chemical actually consumed in the production 
of well-cooked bleaching pulps varies from 18 to 24 pounds per 100 
pounds of wood. 

PRACTICAL VALUE OF RESULTS. 

The experiments discussed in this bulletin have shown in detail 
the effects of certain cooking conditions on the yields and properties 
of the resultant pulp, on the efficiency of the cooking chemicals, and 
on various items affecting costs of production. From a study of 
these results it should be possible for a mill operator so to regulate 
the cooking process as to secure the largest possible yield of pulp of 
the desired quality at a minimum cost for chemicals, fuel, labor, and 
overhead charges hi so far as the operation is affected by the cooking 
conditions considered. 

The clear, sound wood used in the experiments afforded yields of 
good pulp from 10 to 25 per cent higher than the better run of the 
yields reported by pulp mills. Moreover, some of these experimental 
yields were obtained with shorter cooking periods and less chemicals 
than are employed commercially. Although the laboratory results 
may not be equaled in mill practice, the possibility of greatly 
increased efficiency in the process of converting wood into soda pulp 
is indicated. 



APPENDIX. 



ASPEN AS A RAW MATERIAL FOR PAPER PULP. 

DISTRIBUTION AND CHARACTERISTICS OF THE TREE.i 

Aspen (Populus tremuloides Michx.), or quaking aspen, as it is sometimes called, is 
one of the most widely distributed and best-known American trees. Together with 
the closely related European species, Populus tremula Linn., from which paper pulp 
of excellent quality is also prepared, it encircles almost the entire globe. In America 
aspen extends from Labrador to Alaska and southward to Tennessee and Arizona. 
Yet it occurs scatteringly, and pure stands of any extent are comparatively rare. For 
this reason it is not possible to give even approximately the present total stand. In the 
western forests, notably those of Utah and western Colorado, there are vast quantities 
which will doubtless be an important source of future supply. In the past New Eng- 
land furnished most of the aspen pulpwood, and although the supply there is badly 
depleted, considerable quantities yet remain in certain regions, notably in northern 
Maine. 2 

Aspen is a very rapid grower and quickly covers burned or logged-over lands. How- 
ever, it is comparatively short-lived, and the larger trees suffer severely from fire, 
windshake, insects, and fungi. In fact, aspen is defective from decay to a greater 
extent than any other commonly used pulpwood, except perhaps balsam fir. The 
trees ordinarily used for pulpwood are from 5 to 14 inches in diameter. If grown in 
close stands, the trunks are fairly free from knots and limbs. Logging is compara- 
tively easy. 

Aspen wood after cutting is also susceptible to fungous attack unless kept very dry. 
It is particularly perishable in contact with the soil. The ability of the wood to season 
rapidly, especially after being barked, is of much advantage. Nevertheless, mills 
which store a year's supply or more in open yards undoubtedly have a large proportion 
of their older wood affected. The general opinion is that "old wood " produces infe- 
rior pulp and lower yields. 

PROPERTIES AND STRUCTURE OF THE WOOD. 

The wood of aspen is soft, light in weight, not strong, and close grained, but with 
numerous minute, open ducts. The medullary rays are very thin and hardly distin- 
guishable with the naked eye. The color is light brown, the sapwood almost white and 
very thick, often representing 25 to 30 layers of annual growth. In the green or freshly 
seasoned material, however, the difference between heartwood and sapwood is in most 
cases scarcely appreciable. A cubic foot of air-dried wood usually weighs from 25 to 
30 pounds. 

i A more complete discussion of the silvical characteristics of aspen is given in Forest Service Bulletin 
93, The Aspens; Their Growth and Management, by W. G. Weigle and E. H. Frothingham, 1911. 
2 Forest Service Bulletin 93, pp. 13 and 17, 1911. 

41 



42 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

Determinations ' made on sound sticks of aspen varying from 8 to 10 inches in diame- 
ter showed about 62.8 per cent of cellulose. Miiller, quoted by Clapperton, 2 gives the 
following analysis 3 for the poplars: 

Per cent. 

Cellulose. 62. 77 

Resin 1. 37 

Aqueous extract 2. 88 

Water • 12. 10 

Lignin 20. 88 

100. 00 

Since bleached pulp is very nearly pure cellulose, the maximum yield obtainable 
could not be appreciably higher than 63 per cent. 

Aspen wood is made up of three types of structural elements — fibers, vessels, and 
parenchymatous tissue. The latter comprises the medullary ray cells and the rather 
scantily developed parenchyma cells at the end of the year's growth. The structure 
is shown in Plates VIII and IX. In Plate VIII, figure 1, the long tubes running the 
length of the picture are the vessels; cross sections of the medullary rays can be seen 
scattered among the fibers as dark vertical "plates," one cell in width and several in 
height. The ray cells are characterized by exceedingly thin walls, and when the 
wood is cooked for pulp these cells readily dissolve. The vessels are more resistant to 
chemical attack than the parenchymatous tissue, and the fibers, because of their 
relatively thick walls, are least affected by the cooking process. It is also possible 
that the cellulose constituting the fiber walls is more resistant than the cellulose of 
the other elements. In Plate IX, figure 2, the middle lamella or intercellular sub- 
stance appears as a black line between the adjacent walls of the elements. This is 
dissolved in the process of cooking for paper pulp. 

Aspen fibers are comparatively short. Examples of long-fibered woods used in 
paper making are spruce, hemlock, and balsam fir, and of medium-length ones tulip 
tree, sweet gum, and cottonwood. The actual dimensions of aspen fibers vary a 
great deal with the tree and the part of the tree from which secured. Forest Service 
measurements 4 of a large number of fibers of aspen wood showed a range of from about 
0.5 to 1.6 mm. in length and an average length of 1.0 mm. 5 

PULPWOOD CONSUMED. 

At the present time soda, sulphite, sulphate, and mechanical pulps are made from 
aspen and other poplars, but the soda process has always used these woods in by far 
the greater amounts, and they continue to form the chief pulpwood supply for this 
process. The other processes of pulp making have been applied to the poplars within 
recent years only, although it was known 20 or 30 years ago that they could be ground 
for mechanical pulp and could be reduced without difficulty by the sulphite process 
to an easy-bleaching pulp. The properties of the wood and the yields and qualities 
of the pulp made from it, combined with the proximity of an adequate supply and 
its relatively low cost, made this the best wood obtainable for the manufacture of soft, 
easy-bleaching soda pulp. 

i Forest Service Bulletin 93, p. 7, 1911. 

2 Practical Papermaking, p. 43, 1907. 

3 This analysis makes no mention of the ash. According to Sargent (Tenth U. S. Census Rept., Vol. IX) 
the ash in aspen varies from 0.31 to 0.76 per cent, with an average of 0.55 per cent, of the air-dry wood. See 
this report also for further data on the chemical composition and properties of aspen. 

* Forest Service Bulletin 93, p. 7, 1911. 

'- One millimeter is equivalent to approximately one twenty-fifth of an inch. 



PRODUCING SODA PULP FROM ASPEN. 



43 



Table 5. — Consumption of poplar pulpwood and of all pulpwoods in the United States 
for years 1899 and 1905 to 1910, inclusive. 



Year and process. 


Domestic 
poplar. 


Imported 
poplar. 


Total 
poplar. 


All pulp- 
woods. 


Ratio 
domestic 
poplar 
to total 
poplar. 


Ratio 
total 
poplar 
to all 
pulp- 
woods. 




1910.1 


Cords. 
11,613 
2 703 
303, 401 


Cords. 
1, 834 


Cords. 
13, 447 
2 703 
346, 926 


Cords. 
1,180,598 
3 2, 257, 881 
655, 827 


Per cent. 
86.4 
100.0 
87.5 


Per cent. 
1.1 




.03 




43,525 


53.0 




1909.1 






315,717 


45, 359 


361,076 


4,094,306 


87.4 


8.8 




17, 905 

2,930 

282, 041 


3,025 


20, 930 

2, 930 

304, 638 


1,246,121 

* 2, 183, 984 

571,502 


85.6 
100.0 
92.6 


1.7 




.1 




22,597 


53.3 




1908.1 






302, 876 


25, 622 


328,498 


4,001,607 


92.2 


8.2 




16, 734 

3,734 

259, 096 


2,168 
3,023 
17, 462 


18, 902 

6,757 

276,558 


1, 117, 428 

1, 739, 282 

490, 243 


88.0 
55.3 
93.6 


1.7 




.4 




56.4 




1907.1 




t 


279,564 


22, 653 


302, 217 


3, 346, 953 


92.5 


9.0 




16, 903 

1,536 

333, 703 


2,620 


19,523 

1,536 

350, 881 


1,361,302 

2, 059, 496 

541, 862 


86.5 
100.0 
95.0 


1.4 




.1 




17, 178 


64.7 




1906.5 






352, 142 


19, 798 


371, 940 


3,962,660 


94.7 


9.4 




10,475 


2,129 


12, 604 


1, 197, 780 

1, 958, 619 

504, 777 


82.8 


1.1 




.0 




300, 445 


15, 421 


315,866 


95.1 


56.5 




1905.6 






310,920 


17, 550 


328, 470 


3,661,176 


94.6 


9.0 




8,592 


2,800 


11,392 


1, 096, 794 

1, 630, 393 

464, 936 


75.4 


1.0 




.0 




290, 583 


20, 083 


310, 666 


93.5 


66.8 




1899.' 






299, 175 


22, 883 


322,058 


3, 192, 123 


92.9 


10.1 


Total 


s 236, 820 


« 20, 133 


» 256, 953 


1,986,310 


92.3 


12.9 







i Bureau of the Census Circulars, Forest Products No. 1, Pulpwood Consumption (for respective years). 

2 Includes 78 cords reduced by the sulphate process. 

3 Includes 10,188 cords reduced by the sulphate process. 
* Includes 38,000 cords reduced by the sulphate process. 

s Forest Service Circular 120, Consumption of Pulpwood in 1906. 

6 Forest Service Circular 44, Wood used for Pulp in 1905. 

7 Twelfth Census Bulletin 99, Manufactures: Paper and Pulp, Sept. 30, 1901. 

8 Used exclusively by the soda process. 



44 



BULLETIN" 80, U. S. DEPARTMENT OP AGRICULTURE. 



Table 6. — Cost of poplar pulpivood and of all pulpwoods at United States mills in 1907, 

1908, and 1909. 1 



1909. 
Rough wood: 

Domestic poplar 

Imported poplar 

Total poplar 

All pulpwoods 

Peeled wood: 

Domestic poplar 

Imported poplar 

Total poplar 

All pulpwoods 

Rough and peeled wood: 

Domestic poplar 

Imported poplar 

Total poplar 

All pulpwoods 

1908. 

Domestic poplar 

Imported poplar 

Total poplar 

All pulpwoods 

1907. 

Domestic poplar 

Imported poplar 

Total poplar 

All pulpwoods 



Quantity. 



Cords. 

13,953 

2,984 

16,937 

2, 219, 083 

288, 923 

22, 638 

311,561 

1,413,997 

302, 876 

25,622 

328, 498 

1,001,607 



279,564 

22, 653 

302, 217 

3,346,953 



352,142 

19, 798 

371,940 

3, 962, 660 



Total cost. 



Average 

cost per 

cord. 



Dollars. 

72,555 

24,469 

97,024 

17, 608, 736 

2,337,461 

179,019 

2,516,480 

12, 169, 393 

2,410,016 

203, 488 

2,613,504 

34,477,540 



2,237,631 

182, 143 

2, 419, 774 

28,047,473 



2, 763, 889 

167,039 

2,930,928 

32, 360, 276 



Dollars. 
5.20 
8.20 
5.72 
7.94 

8.09 
7.91 
8.07 
8.61 

7.96 
7.94 
7.95 
8.62 



8.01 
8.04 
8.00 
8.38- 



7.85 
8.44 
7.88 
8.17 



1 Bureau of the Census Circulars, Forest Products No. 1, Pulpwood Consumption (for respective years). 
Prices quoted are based on f. o b. mill deliveries. 
s Includes 368,527 cords of rossed wood at an average cost of 812.75 per cord. 

While there are no statistics of the consumption of aspen pulpwood alone, the Census 
figures ' for the consumption of "poplar" are of interest. The woods grouped under 
this name consist of several species of the true poplars, of which aspen is by tar the most 
important, and doubtless include also a small amount of "yellow poplar" or tulip tree 
(Liriodendron tulipifera Linn.). The poplars collectively stand third in the amount 
cut for pulpwood, being exceeded only by spruce and hemlock. Table 5 shows the 
amount of poplar pulpwood used, by processes, in 1899 and each year from 1905 to 
1910, inclusive. The cost of poplar per cord in 1907, 1908, and 1909 is shown in Table 
6. The average cost per cord for poplar pulpwood did not change materially during 
the period 1907 to 1909, though the average cost per cord for all pulpwoods steadily 
advanced. 

PAPER PULP FROM ASPEN. 

CHARACTERISTICS AND PROPERTIES. 



Aspen soda pulp, when unbleached and dry, is a very light brown or light reddish- 
brown much resembling ordinary blotting paper. While fairly tenacious, the pulps are 
usually very soft and bulky, whether bleached or unbleached. The softness of the pulp 
may be partly due to the fact that its natural resin content is normally very low (0.05 
per cent) as compared with ordinary sulphite pulp (0.5 per cent). Aspen soda pulp 
is easily bleached to a good white color, though in some cases there may be a slight 
reddish tinge. For well-cooked pulp very low amounts of bleaching agents are 
required, and the loss on bleaching (from 6 to 10 per cent in commercial practice) 
is comparatively small. The following table by Griffin and Little 2 affords a eom- 

1 For statistics on the consumption of poplar pulpwood by Canadian mills, see bulletins 1 2, 26, and 30, of 
the Forestry Branch, Canadian Department of the Interior, 1909-1912. 

2 Chemistry of Papermaking, p. 280, 1894. 



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PRODUCING SODA PULP FKOM ASPEN. 



45 



parison between the amounts of bleaching powder required for pulps from poplar 
(including aspen) and for other pulps: 

Table 7. — Amount of bleaching powder required Jor commercial pulps. 



Kind of pulp. 


Bleaching 

powder per 

100 pounds 

of pulp. 




Pounds. 
18-25 
12-15 
10-15 

15-25 
14-20 






Sulphite spruce 

Sulphite poplar 



The individual fibers in aspen soda pulp are of the following dimensions: 1 Length, 
from 0.67 to 1.49 mm., averaging 0.99 mm.; breadth at the middle, from 0.01 to 0.03 
mm., averaging 0.02 mm. ; approximate thickness of cell walls, 0.002 mm. ; ratio of length 
to breadth, 50:1. The fibers are slender, gradually tapering to needle-pointed ends. 
They are pliable and mpstly curved, although many are nearly straight. While 
sometimes twisted and often swollen in nodes, with slight constrictions, they are 
never badly tangled or knotted . Aspen fibers tend to be more nearly circular in cross 
section than those from conifers. Other distinguishing characteristics are the medium 
length of the fibers and the presence, except in ' ' overcooked " pulps, of remnants of the 
larger wood vessels and parenchymatous tissue. The vessel walls have closely packed 
bordered pits with hexagonal contour, and the inside walls are not marked with spiral 
thickenings, as is the case with some species. The vessel ends have open pores without 
gratings, which distinguishes aspen pulp from that of the tulip tree or yellow poplar 
sold in European markets under the name "Amerikanische Aspenzellulose." 2 

YIELDS. 

The yields reported by a number of American soda-pulp mills operating on aspen 
and other woods-are given in Table 8. 

Table 8. — Yields of soda pulps reported by various mills. 3 



Species of wood. 



Yield per 
cord.* 



Poplar: 

100 per cent domestic . 
Do 



Do. 
Do. 



59 per cent domestic, 41 per cent imported . 

100 per cent domestic 

Do. 



Pounds. 
1,000 
1,040 
1,050 
1,050 
1,075 
1,102 
1,139 
1,144 
1,153 
1,161 
1,170 
1,191 
1,200 
1,209 

1 The dimensions and characteristics were determined microscopically from 52 separate fibers from the 
26 different cooks made in these experiments. No effort was made to select extremely long or extremely 
short fibers. See also photomicrographs of pulps, Plates II to VII. 

2 Litchauer, Zentr. f. d. Oesterr.-ung. Papierindustrie, p. 822, vol. 23, 1905. 

3 Each value is the report of 1 mill, received during the period 1907-1909. 

* On the percentage basis the yields of soda pulp from poplar also vary widely. Reid (Jr. Soc. Chem. 
Ind., pp. 273-276, vol. 5, 1886) reports a yield of 41 per cent. De Cew (Jr. Soc. Chem. Ind., pp. 561-563, vol. 
26,1907) cites a yield of 44 per cent, or 1,150 pounds per cord, from large-tooth aspen. Sindall(Paper Tech- 
nology, p. 201, 2d ed. 1910) mentions a yield of 52 per cent, which is unusually high for commercial 
practice. 



33 per cent domestic, 67 per cent imported . 

100 per cent domestic 

59 per cent domestic, 41 per cent imported. 

100 per cent domestic 

91 per cent domestic, 9 per cent imported . . 

100 per cent domestic 

90 per cent domestic, 10 per cent imported. 



46 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

Table 8. — Yields of soda pulps reported by various mills — Continued. 



Species of wood. 



Yield per 
cord. 



Poplar 11 per cent and pine 89 per cent 

Poplar 91 per cent and chestnut 9 per cent 

Poplar 75 per cent and gum 25 per cent 

Poplar 95 per cent and gum 5 per cent 

Poplar 12 per cent, pine SS per cent, and gum small amount 

Poplar 3 per cent, pine 25 per cent, and maple 72 per cent 

Poplar 32 per cent, pine 52 per cent, and hemlock 16 per cent 

Poplar 13 per cent, pine 1 per cent, and chestnut 86 per cent 

Poplar 7 per cent, pine 43 per cent, maple 45 per cent, and basswood 5 per cent 

Poplar 9 per cent, pine 34 per cent, maple 19 per cent, beech 19 per cent, other hard woods 19 

per cent 

Poplar 56 percent, maple 7 percent, and basswood 37 percent 

Poplar 40 per cent; birch, maple, beech, and basswood 

Poplar 30 per cent, Cottonwood 30 per cent; maple, buckeye, willow, and lime 10 per cent each. . 



Pounds. 

1,000 
800 

1,000 

1,139 
985 
948 
862 
800 

1,014 

794 
1,043 
1,160 
1,000 



The several yields were all determined from the amounts of wood consumed annu- 
ally by each mill and the total production of pulp in the same time. The yields 
represent air-dry, bleached pulp, except for a few of the mills which used coniferous 
woods, together with the poplars. 

The experimental work of the Forest Service shows that yields of over 55 per cent 
(bone-dry basis) of unbleached pulp (see Table 11) can be obtained. Even the lowest 
yield of good unbleached pulp was not less than approximately 45 per cent. A yield 
of 55 per cent amounts to over 1,450 pounds of bone-dry, unbleached pulp, or over 
1,600 pounds of air-dry, bleached pulp,- per 100 cubic feet of solid wood. The average 
12S-foot cord of peeled aspen contains approximately 90 cubic feet of solid wood, 1 
and on this basis would produce 1,440 pounds of air-dry, bleached pulp. 

It seems evident, therefore, that considerably higher yields can be obtained from 
aspen than are secured in commercial practice. One of the many reasons for the 
lower yields of the commercial plants is probably the quality of the wood. 2 In the 
Forest Sendee tests the wood used was clear and sound, all defective material having 
been culled. 

USES. 

The principal use of soda poplar or aspen pulp is in the bleached form for such 
papers as book, magazine, antique, coated, lithograph, map, card, cover, common 
envelope, and writing; and wood blotting papers; also the soft, bulky papers some 
times required for special purposes. In making these papers longer-fibered pulps, 
that is, bleached rag or sulphite wood pulps, are mixed with the soda pulp in various 
proportions up to 80 per cent of the whole. These other fibers are added mainly for 
the purpose of strengthening the soda pulps, and their proportion in the mixture 
depends upon the desired quality of the product. The use of considerable amounts 
of soda poplar pulp is favored in some cases because it imparts to the sheet of paper a 
bulkiness and opacity not readily obtainable with ordinary sulphite or rag pulp alone. 
The addition of the long-fibered pulps tends to increase the cost of the products, 
but gives them more lasting qualities. These mixed pulps lend themselves with 
particular ease to the various paper-making operations, such as sizing, coloring, 
beating, and running on the paper machine. 

The amount of various kinds of wood pulps used in the United States in 1909 and 
1899 is shown in Table 9. 

1 Forest Service Bulletin 36 (rev. ed., 1910), p. 113, Woodman's Handbook, by II. S. Graves and E. A. 
Ziegler; also "Factors influencing the volume of solid wood in the cord," by R. Zon, Forestry Quarterly, 
p. 126. No. 4, vol. 1. 

2 In some earlier experiments by the Forest Service considerably lower yields were obtained, which were 
attributed to the inferior quality of the wood. See Table 15. 



PRODUCING SODA PULP FROM ASPEN. 



47 



Table 9. — Amounts of mechanical, soda, and sulphite wood pulps used in the United 

States. 



Kind of pulp. 


Total pulps. 


Imported pulps. 


• 19091 


18992 


19091 




Tons. 
1,323,000 
304, 000 
1,200,000 


Per cent. 
4"7 
11 
42 


Tons. 
586, 374 
171, 959 
416, 230 


Per cent. 
50 
15 
35 


Tons. 
119,500 
9,500 
172, 400 


Cost. 

$2, 723, 000 




398, 000 




8, 142, 000 






Total 


2, 827, 000 


100 


1, 174, 563 


100 


301,400 11.263.000 






' 



1 Bureau of the Census— Paper and Wood Pulp Statistics; preliminary report for 1909, issued Apr. 26, 
1911, p. 3. 

2 Bureau of the Census— Bulletin 99 of the Twelfth Census, pp. 10, 12, 1901. 

RECORDS OF THE SERIES TESTS. 

Tables 10 to 14 give the data for the several groups of tests in which the cooking 
conditions were varied in series. 

EXPLANATION OF DATA. 

The following column headings may need explanation: 

Water in chips. — The quantity of water or moisture in the chips as charged is ex- 
pressed in percentage of water based on the calculated bone-dry weight of the chips. 

Initial concentrations of digester liquors. — The caustic soda (NaOH) and the sodium 
carbonate (Na 2 C0 3 ) concentrations are determined by analysis of the stock soda 
solution, and are calculated on the basis of total liquid in the charge, including mois- 
ture in the chips. The total sodium oxide (Na 2 0) is calculated from the proportions 
of NaOH and Na 2 C0 3 , each reduced to the sodium-oxide basis. Grams-per-liter 
concentrations may be converted into the equivalent pounds per gallon by multi- 
plying by 0.00834. What is sometimes erroneously called percentage concentrations 
may be obtained by dividing grams-per-liter concentrations by 10. 

Causticity of liquor. — This represents the ratio of sodium oxide in the caustic soda 
to the total sodium oxide. 

Initial volume of digester liquors. — The digester liquors consist of the stock soda solu- 
tion and water charged, together with the water in the chips as charged. 

Chemicals charged. — The quantities of the several chemicals charged are their dry 
weights based on the chemical formulae indicated. 

Duration of cooking. — Compare data with figure 3. 

Apparent condensation. — This is obtained by subtracting the amount of digester 
liquors at the start of the cook from the amount of liquid in the digester (as read from 
a water gauge) just before relieving the pressure, and blowing the digester at the end 
of the cook. It affords a rough measure of the amount of water condensing from the 
steam used for cooking. 

Yields. — The yields of total crude pulp, screenings, and screened pulp are calcu- 
lated to a bone-dry basis, and are expressed as a percentage of the calculated bone- 
dry weight of the chips. The total crude pulp is the total fibrous material and un- 
cooked chips blown from the digester. 

Yields of pulp per solid cord. — In calculating yields to pounds per cord of wood a 
"solid cord" is considered equivalent to 100 cubic feet of solid wood, green volume, 
knot free. For the aspen tested, the calculated bone-dry weight per " solid cord " was 
2,668 pounds. The yield of bleached pulp, which is given on the air-dry basis (10 per 
cent moisture), is computed by deducting the loss on bleaching and considering 90 
pounds of bone-dry pulp equal to 100 pounds of air-dry pulp. 



48 BULLETIN 80, IT. S. DEPABTMENT OF AGBICULTUBE. 

Color ratings. — These are numerical expressions of the colors of the unbleached 
pulps, and were determined on machine-made sheets by means of a tint photometer, 
according to the method described on page 54. 

Average strength. — The strength tests were conducted on machine-made sheets of 
unbleached pulp in the air-dry condition. 1 The methods of testing are described on 
page 54. 

Bleach required. — This represents the parts of bleaching powder (35 per cent availa- 
ble chlorine') required to bleach 100 parts bone-dry weight of unbleached pulp to the 
commercial white color. 

Loss on bleaching. — This is based on the calculated bone-dry weight of unbleached 
pulp lost when bleaching it to the commercial white color, with the stated per cent of 
bleach. 

Causticity of black liquor. — This was determined by analysis, and is the ratio of the 
sodium oxide in the caustic soda existing as such in the black liquor to the total sodium 
oxide in the black liquor. The latter represents the total titratable alkali in the ash 
resulting from calcining the black liquor. 

Efficiency in the use of NaOE. — This is the ratio of the amount of caustic soda actu- 
ally consumed during the cooking operations to the amount of caustic soda originally 
in the charge. It is calculated from the causticity of the black liquor, assuming that 
the soda chemicals in the black liquor are all titratable as sodium carbonate, after the 
liquor has been reduced to an ash. 

Wood, soda ash, and bleach employed per ton of pulp. — The volume of wood is based 
on the average bone-dry weight of aspen used in the tests (2,668 pounds per solid cord). 
The soda ash represents the total soda ash of 99.1 per cent purity (58 per cent Na 2 0) 
necessary to furnish the chemicals employed in cooking, assuming that no loss of 
alkali occurs in causticizing. The bleaching powder represents the dry weight of this 
chemical, losses in making the bleaching solutions being disregarded. 

i The failure of the Sehopper tests to show even relatively uniform variations in the strength of pulp as 
affected by changes in the cooking conditions can not be explained unless that the pulps were not suitable 
for these tests. 



PKODUCING SODA PULP FEOM ASPEN. 



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t^ t~ t^ t^l^ 


r^* 00 00 CO 
►N CO CO CO 
COCO CO 


t-- OO 00 00 00 OO 
CO CO CO CO CO CO 
CO CO CO CO CO CO 


oooo 
coco 
coco 




00 00 00 00 00 
CO CO CO CO CO 
CO CO CO CO CO 


•qoui a.renbs jad ams 
-said aSneS umraixi3j\[ 


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^rnrHr-l 


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§g 




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d m 
2.8 
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eSneS umuiixeui % y 


c'ooo 


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CO CO CO CO SO CO 


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CJJNIQ93-H 


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CN<M ^N«« 


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'TOOX 


S^OOO 
[g CO 00 00 


oooooo 

t- t> t- t- t*- 1~ 


o-»i 
cqco 




ooooo 

OOO CO ■* CM 


Chemicals charged 
per 100 pounds of 
chips (bone-dry 
basis). 


"O^N m«X 


OOO o 
^ COrHC~ 

[^COrrrH 

Hcmcmcm 


t>oosa>HO 

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"HCBN 


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gmcoco 

HcOCNCM 


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11 CM 

o>o 

CM CM 




OOCOCMO 

OOOHO 

IO IO -t IO lO 
Ci CM CM CM CM 


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jo ' punod jad sioribji 
jajsaSip jo aumjoA rei^rai 


•scooso 

E3 tOCO Ml 


Tt< CO OS CO ON 
OilNOlNOlM 
*0 lO "^ CO CO CM 


MHO 
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Ml M< CO 00 CM 

CO CO CO CO CO 
CO CO CO CO CO 


•SOO^N 


g .t^CMOO 

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CO CO O* tN ^f "^ 


r-Tti 

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■fll-f COOrl 
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"HOBN 


«j .own 

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<M OHtOON 

OONHOOJ 
0OO0N.N00N. 


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coco 




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l.*OrtO 


CM iC (N 00 ^ ^ 

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50 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



O 



a, 



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a 

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K 


o w 

°°^ 

K * 

pq 


•(siscq A"jp-ouoq) 
sdrqo jo punod jad 
uoiresnapnoo :rcra.rBddy 


Galls. 
.980 
.925 
.865 
'.900 
.920 
.875 

1.243 

1.240 
U. 185 

31.014 


•qotn 

ajcnbs jad \d\ui ja^sag 
-tp at; ajnssajd urea} s 


Lbs. 
132 
127 
114 
114 
115 
117 

114 
115 
116 

116 


•sajnirejad 
-uia; Sut^ooo umunxTspj; 


° C. 

177 

173.5 

170 

166.5 

162 

158 

170 
170 
170 

170 


n. o -*f oo ^ -*f co oooooo oo 

^ »o -* CO CO cm ~* CO CO CO CO 
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&J 


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0^0050000 OOO O 

f2 oo r^ oo oo oo od ooocoo oo 


Chemicals charged 
per 100 pounds of 
chips (bone-dry 
basis). 


■O s *N m»X 


Lbs. 

19.73 
19.92 
19.92 
19.92 
19.92 
19.94 

19.85 
19.82 
19.85 

19. 83 


• £ O0 s ^N 


Lbs. 
.57 
.93 
.91 
.91 
.90 
.94 

.75 
.75 
.75 

.74 


'HO^N 


Lbs. 
25.00 
25.00 
25.00 
25.00 
25.00 
25.00 

25.02 
25.00 
25.02 

25.00 


•(siseq i.rp-auoq) sdrqo 
jo ' punod jad sjonbq 
jajsagip jo aurrqoA ren'raj 


Galls. 
.375 
.375 
.375 
.375 
.375 
.375 

.273 
.333 
.429 

.599 


CJD 
3 

A 
o 

o 

3 


•AVHorisriBo 


Per ct. 
98.3 
97.3 
97.3 
97.3 
97.4 
97.3 

97.8 
97.8 
97.8 

97.8 


a 

_o 

03 

P 

3 

o 

p 

o 
o 

1 


•O^N ibjox 


Gm. per 
liter. 
63.1 
63.8 
63.7 
63.7 
63.7 
63.7 

87.2 
71.4 
55.5 

39.7 


• S 00 5 ^N 


Gm. per 
liter. 
1.8 
3.0 
2.9 
2.9 
2.9 
3.0 

3.3 

2.7 
2.1 

1.5 


"HO B N 


3 .OOOOOO 0»iO »-< 

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^-^OOOOOOOOOOOO ~-< OJ < , tea 
C3 


•sdrqo m Jare^ 


l-^nOOOCOfl (MCNCN CN 

we ... 

ft^ S 05 05 05 OO 05 o» 000000 OO 


•(siseq Xjp-auoq) 
paSjcq'o sdrqo jo iqSiajVV. 


oooooo cococo eo 
c^OOOOOO ooo o 

^OOOOOO 050505 OS 

H ■■* Tr •**< ^ -^ ^* cococo co 


O j 

5 o 
ci* o 


COi-Ht^CO*0-cH i-I^IQ 00 
• r~l ^ CN CN CN CN 

P3 :- ^ i- ~ ~ — ~ C L- C 

S p, p, p, p, p, p, ppp p 


"ON 3looo 


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Group IV 



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PRODUCING SODA PULP FROM ASPEN. 

Table 11. — ■ Yields of experimental pulps. 



51 





Cook 
No. 


Yields (bone-dry basis). 


Yields of 

un- 
bleached 

pulp 
(bone- 
dry basis) 
per solid 

cord. 


Yields of 
bleached 

pulp 
(air-dry 

basis) 
per solid 

cord. 


Kind of test. 


Total 
crude 
pulp. 


Screen- 
ings. 


Screened 

un- 
bleached 
pulp. 




1 
2 
3 

4 
5 
6 

7 
8 
9 

10 
ill 
12 
13 
14 
15 
16 

17 
18 
19 
20 
21 
22 

23 

24 
25 

26 


Per cent. 
48.01 
50.34 
49.31 

46.48 
50.01 
44.67 
52.63 
55. 57 
58.30 

50.36 


Per cent. 

0.05 

.03 

.02 

.01 
.01 
.01 
.03 
.01 
13.02 

.08 


Per cent. 
47.96 
50.31 
49.29 

46.47 
50.00 
44.66 
52.60 
55.56 
45.28 

50.28 


Pounds. 
1,279 
1,342 
1,314 

1,240 
1,334 
1,191 
1,402 
1,482 
1', 208 

1,341 


Pounds. 
1,406 




1,475 
1,444 

1,372 




1,467 
1,308 
1,533 
1,625 
1,315 

1,487 








51.72 
52.49 
53.70 
55.58 
58.12 

48.67 
50.02 
52.55 
54.97 
54.85 
57.88 

49.18 
51.61 
50.78 
53.58 


.04 
.05 
.09 
.44 
19.00 

.01 
.02 
.04 
.02 
.09 
.13 

.02 
.01 
.01 
.03 


51.68 
52.44 
53.61 
55. 14 
39.12 

48.66 
50.00 
52.51 
54.95 
54.76 
57.75 

49.16 
51.60 
50.77 
53.55 


1,378 
1,400 
1,429 
1,471 
1,043 

1,298 
1,335 
1,400 
1,465 
1,460 
1,541 

1,311 

1,376 
1,354 
1,429 


1,524 
1,524 
1,558 
1,586 
1,109 

1,422 




1,461 
1,530 
1,612 
1,595 
1,666 

1,432 




1,521 
1,483 
1,573 



1 Cook spoiled, due to defect in apparatus. 



52 



BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 



5 s 



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WiOOliOCN •^OOi-HtM-^I 

HHH-* CO HCOiOC 



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asooooooos ososooosooas oocooooo 



rH rH ■-* "^ t-- 

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PRODUCING SODA PULP PROM ASPEN. 
Table 13. — Caustic soda consumed during cooking. 



53 











NaOH 


NaOH 










consumed 


consumed 




Cook 

No. 


Causticity 


Efficiency 


per 100 


per 100 


Kind of test. 


of black 


in the use 


pounds of 


pounds of 




liquors. 


ofNaOH. 


wood 


unbleached 










(bone-dry 


pulp (bone- 










basis). 


dry basis). 






Per cent. 


Per cent. 


Pounds. 


Pounds, 


Preliminary 


1 
2 












13.4 


86.2 


23.1 


45.9 


* 


3 


2.2 


97.8 


26.2 


53.2 




4 


22.3 


77.0 


30.6 


65.9 

54.6 




5 


21.4 


77.9 


27.3 




6 


14.3 


85.3 


25.6 


57.4 




7 


15.3 


84.2 


18.9 


36.0 




8 


17.2 


82.1 


16.4 


29.5 




9 


2.8 


97.1 


14.6 


32.3 




10 

ill 

12 


4.7 


95.0 


23.7 


47 1 








4.6 


95.4 


23.9 


46.2 




13 


3.4 


96.5 


24.1 


46.0 




14 


10.2 


89.6 


22.3 


41.6 




15 


18.0 


80.7 


20.3 


36.8 




16 


25.5 


74.0 


18.5 


47.3 


Group III 


17 


5.7 


94.2 


23 6 






18 


4.7 


95.2 


23.8 


47.6 




19 


14.4 


85.2 


21.3 


40.6 




20 


20.1 


79.3 


19.8 


36.1 




21 


27.1 


72.1 


18.0 


32.9 




22 


26.0 


73.2 


18.3 


31.7 


Group IV 


23 


19.4 


80.2 


20 1 


40.9 
39.5 




24 


18.1 


81.5 


20.4 




25 


17.8 


81.8 


20.5 


40.4 


1 


26 


10.3 


89.5 


22.4 


41.9 



1 Cook spoiled, due to defect in apparatus. 

Table ]4. — Wood, soda ash, and bleach employed per 2,000-pound ton of air-dry pulp 
(10 per cent moisture) based on experimental results. 





Cook 

No. 


Unbleached pulp. 


Bleached pulp. 


Kind of test. 


Wood. 


Soda ash 

(58 per 

cent 

Na 2 0). 


Wood. 


Soda ash 

(58 per 

cent 

Na 2 0). 


Bleaching 

powder 

(35 per 

cent 

available 

chlorine) . 




1 
2 
3 

4 
5 
6 

7 
8 
9 

10 

Ul 

12 
13 
14 
15 
16 

17 
18 
19 
20 
21 
22 

23 
24 
25 

26 


Solid 
cords. 
1.41 
1.34 
1.37 

1.45 
1.35 
1.51 
1.28 
1.22 
1.49 
1.34 


Pounds. 
1,853 
1,308 
1,367 

2,117 

1,738 

1,661 

1,057 

901 

828 

1,259 


Solid 
cords. 
1.42 
1.36 
1.38 

1.46 
1.36 
1.52 
1.30 
1.23 
1.52 

1.34 


Pounds. 
1,872 
1,322 
1,384 

2,126 
1,757 
1,681 
1,074 
912 
844 

1,259 


Pounds. 


Group I 


145.6 
136.5 

108 4 




127.4 
136.5 
164.6 
255.6 
532.5 

144 3 






Group III - 


1.31 
1.28 
1.26 
1.22 
1.72 

1.38 
1.35 
1.28 
1.22 
1.23 
1.17 
1.38 
1.31 
1.33 
1.26 


1,191 
1,172 
1,145 
1,177 
1,571 

1,258 
1,235 
1,178 
1,126 
1,128 
1,071 

1,254 
1,191 
1,214 
1,149 


1.31 
1.31 
1.28 
1.26 
1.80 

1.41 
1.37 
1.31 
1.24 
1.25 
1.20 

1.39 
1.32 
1.35 
1.28 


1,196 
1,196 
1,167 
1,211 
1,642 

1,276 
1,254 
1,196 
1,137 
1,148 
1,101 

1,276 
1,199 
1,232 
1,160 


181.2 
174.7 
192.7 
278.1 
432.3 
127 8 


Group IV 


146.2 
164.7 
182.1 
201.2 
351.2 

155.7 




162.9 
173.5 
200.0 



1 Cook spoiled, due to defect in apparatus. 



54 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

METHODS FOR AUXILIARY TESTS. 

In determining bone-dry weights, properties of pulps, and concentrations of soda 
liquors, the following methods were employed: 

BONE-DRY WEIGHTS. 

In practically all determinations involving exact quantities of wood, pulp, or 
screenings, either actual or calculated bone-dry weights were used. The actual 
bone-dry weight is the weight of the material after having been dried to constant 
weight in an oven with good circulation of pure air at a temperature of 104-106° C. 1 
Usually instead of drying the entire quantity of material, its "bone-dry factor," or 
the ratio of the bone-dry weight to the weight before drying, was determined by 
means of a small sample. The calculated bone-dry weight is the weight obtained 
by use of this factor. The errors in calculated bone-dry weights were found by actual 
test to be less than 0.3 per cent. 

PROPERTIES OF UNBLEACHED PULP. 

Color. — The color of a pulp was determined by visual observation and also by 
means of an Ives new construction tint photometer. The standard for comparison 
was a block of magnesium carbonate, which affords photometer readings of 100 each 
for the red, green, and blue color screens used. The sum of the three readings for 
a pulp measures its "whiteness," and this sum subtracted from 300 2 (the sum of the 
three readings for a surface as white as the standard) measures the "parts black" rat- 
ing of the pulp. The higher the "parts black" value the darker is the pulp. This 
method of expressing relative "darkness" of different pulps is reliable only when 
the pulps are of approximately the same hue, as in the case of these experiments. 

Skives. — Shives in pulp are the small bundles of wood fibers which were not reduced 
by the cooking and subsequent operations, and which were not removed by the pulp 
screens. For the determination, a three-tenths-gram portion of pulp, the bone-dry 
factor of which was known, was thoroughly broken up in a small Erlenmeyer flask 
and deposited on a 70-mesh sieve in an even deposit or sheet covering 9.66 square 
inches. This sheet was "couched" on a silk cloth and then transferred to a glass 
plate and dried in an oven. When the plate with the deposit was placed in front of 
an incandescent lamp the shives could easily be counted with the eye. In cases 
where the number was large, a glass plate divided into quarter-inch squares was 
placed on top of the pulp and a small area was examined instead of the whole. Know- 
ing the area examined and the bone-dry weight of the pulp sheet, the number of 
shives per gram of bone-dry pulp could be calculated. 

Ash. — The ash was determined by burning a bone-dry sample of unbleached pulp 
of known weight in a platinum or porcelain dish over a Bunsen flame until the ash 
produced was free from carbon and of a white or grayish-white color. The percentage 
of ash is based on the bone-dry weight of the pulp. 

Strength. — The strength of the pulp sheets made on the paper machine was deter- 
mined by a Mullen paper tester and by a Schopper breaking-length testing instrument. 
The pulp was tested in the ordinary air-dry state for the conditions that prevailed 
in the laboratory. The Mullen test, or "pop test" as it is sometimes called, was 
made by clamping a single sheet, accurately measured for thickness, between a rubber 
diaphragm and a polished metal ring, and then, by means of liquid under pressure, 
forcing the diaphragm against the pulp sheet until it burst through the aperture. 
The pressure on the liquid in pounds per square inch, or "points," is read from a 



1 The weight was considered constant when the decrease was not more than 0.1 per cent during an addi- 
tional hour's drying at this temperature. 

2 At the time of these experiments the shutter of the instrument used had been injured and could not 
be opened more than 64.7 points. The other aperture was then reduced to this size and the value 64. 7 
was used in place of 100 for a wide-open aperture, and 194 (3 t^mes 64.7) was used in place of 300. The results 
obtained for the various pulps were sufficiently accurate for comparison with each other. 



PRODUCING SODA PULP FROM ASPEN. 55 

gauge. For each pulp 20 sheets whose thickness varied between 0.010 and 0.011 inch 
were tested. The average strength in pounds per square inch per 0.001 inch thickness 
is the quotient of the average test value divided by the average thickness in thou- 
sandths of an inch. A quantity one-tenth of this value is sometimes used in express- 
ing results, and is called the "strength ratio." l The Schopper tester measures in 
kilograms weight the tensile stress required to break a strip of pulp 15 mm. wide. At 
the same time the instrument registers the "per cent stretch," which is the strain or 
elongation of the strip just before breaking, and is expressed as a percentage of the 
original length. The "breaking length" is the length of sheet which, if suspended, 
would break of its own weight, and when expressed in meters is determined by multi- 
plying the weight in kilograms required to break the strip by its testing length in milli- 
meters (180 mm.), and dividing the product by the weight in grams of the portion 
of the strip subjected to test. Five strips of pulp were tested in the "machine 
direction" of the sheet and five across the machine direction, and the average 
values for the two directions determined. 

Bleach required.— -The bleaching solution was made by mixing bleaching powder 
(calcium oxy-chloride or chloride of lime) with water and allowing the mixture to 
settle so that a clear solution was obtained. The strength of this solution was deter- 
mined by titrating 5.00 cc. against fifth normal arsenious acid solution, using a solu- 
tion of starch paste and potassium iodide as indicator. The number of cubic centi- 
meters of arsenious acid used, multiplied by 4.0514, gave the strength of the bleaching 
solution in grams per liter of "35 per cent bleach," or bleaching powder, in which 35 
per cent of its weight is chlorine available for bleaching purposes. The bone-dry 
weight (about 50 grams) of the pulp sample used for the bleaching determination was 
first calculated by means of its bone-dry factor. The sample was then thoroughly 
broken up in water 2 to form a uniform pulp mixture. A quantity of the bleaching 
solution containing a known weight of "35 per cent bleach " was added and the mix- 
ture diluted with water 2 to approximately 2,500 cc. This mixture was kept at a 
temperature of 40° C. until the bleach was exhausted, as determined by starch -iodide 
indicator. The bleached fiber was then thoroughly washed free from bleach residues 
and made up into sheets on a small hand mold. These sheets, when air-dry, were 
compared with air-dry standard color sheets made in a similar manner from five or six 
commercially bleached soda pulps mixed in equal proportions. If the first determi- 
nation on the experimental pulp did not give as white a color as the standard, the 
process was repeated on other samples until the standard color was attained as nearly 
as possible. 3 The weight of 35 per cent bleach required to produce the standard 
color is expressed as a percentage of the bone-dry weight of the pulp. The bleaching 
operations were performed in enameled jars provided with agitators and placed in a 
tank of water whose temperature could be regulated by an electric heater. It was 
found best to start the bleaching in the late afternoon or evening, so that the bleach 
was exhausted sometime the next morning. The comparisons with the standard 
color sheets should be made at about the same time each day, using light from a north 
window. 

Loss on bleaching. — For determining the loss on bleaching, a sample of about 2 
grams of pulp was thoroughly broken up in water and bleached in a 250 cc. Erlen- 
meyer flask, using as near as possible the conditions which produced the standard 

i "Strength factor" or "points per pound" is distinguished from "strength ratio" by the former being 
obtained by dividing the "pop test" by the weight in pounds of a ream of paper. The size of a ream varies, 
but for a standard of comparison a ream of 500 sheets, 24 by 36 inches, is usually preferred for determining 
the strength factor. 

2 The water should be neutral so far as its action on pulp and on bleaching powder solution is concerned. 
The use of distilled water is preferable. 

3 Actual tests have shown that this method gives results almost identical to those secured in pulp-mill 
operations. The method of determining the amount of bleach required by adding an excess of bleaching 
powder and titrating the unconsumed excess after the pulp is bleached sufficiently white, gives much 
lower results. 



56 BULLETIN 80, U. S. DEPARTMENT OF AGKICULTUKE. 

color in the samples tested for the determination of the amount of bleach required. 
The bleached sample was thoroughly washed, first with hot distilled water and after- 
wards with ethyl alcohol. Its bone-dry weight was then determined. The per- 
centage loss on bleaching is based on the bone-dry weight of the unbleached pulp, 
which had been calculated from its bone-dry factor. 

Microscopic examinations. — Representative portions from the pulp sheets were 
soaked in water, teased apart with a needle, stained with Bismarck brown, dehydrated 
with absolute ethyl alcohol, cleared in xylol, and made into permanent mounts with 
Canada balsam. Photomicrographs of these mounts magnified 65 diameters were used 
in studying the individual fiber characteristics. Further microscopic study of each 
of the individual mounts was also made, using different magnifications, and such 
features were observed as the apparent strength of cell walls, the prominence of cell 
markings and the presence of vessels, fiber bundles (shives), and ray cells. The 
general shape and condition of the fibers and the distinguishing characteristics for 
the species were noted. By means of a micrometer eyepiece about 50 unbroken 
fibers from the various mounts were measured for length and breadth at the middle 
of the fibers, and the average thickness of the cell walls was roughly estimated. The 
fibers were selected at random, no effort being made to select extremely long or short 
ones. 

ANALYSES OF SODA LIQUORS. 

The caustic-soda solutions charged and the black liquors from the leached pulps 
were examined for their contents of cooking chemicals, in the first case to calculate 
sizes of charges, and in the second to determine the consumption of caustic soda during 
cooking. 

Caustic soda liquor. — The examination of the caustic soda liquor was conducted as 
follows: A 10 cc. portion was titrated against normal sulphuric acid, using phe- 
nolphthalein as first indicator and methyl orange indicator to finish the titration. 
Letting Y=the number of cubic centimeters of normal acid solution required for 
the first end point and X=the number of cubic centimeters required for the final 
end point, the following equations were used for calculating the concentration of 
caustic soda (NaOH) and the causticity: 

4 (Y-(X-Y))=grams per liter of NaOH. 
100 (Y-r(X-Y)) 



X 



=per cent causticity. 



Black liquor. — The examination of black liquor was conducted as follows: 

(1) A 50 cc. portion of black liquor was evaporated to dryness in a platinum dish. 
The residue was ashed over a Bunsen burner and the soluble salts were leached out 
with hot distilled water. The entire solution obtained was titrated with normal sul- 
phuric acid, using methyl orange as indicator. The number of cubic centimeters of 
acid required to produce the end point multiplied by 0.62 gives the grams per liter 
of total sodium oxide (Na 2 0) in the black liquor. 

(2) A 100 cc. portion of the same black liquor was mixed with 50 cc. of 10 per cent 
barium chloride solution in a 500 cc. calibrated flask. The mixture was then diluted 
to 500 cc. with neutralized or freshly distilled water free from carbon dioxide and 
thoroughly agitated. After settling, 50 cc. of the clear supernatant liquor were titrated 
with tenth normal hydrochloric acid, using phenolphthalein as indicator. The num- 
ber of cubic centimeters of acid required for the end point multiplied by 0.401 gives 
the number of grams per liter of free caustic soda (NaOH) in the black liquor. 

(3) The causticity of the black liquor was calculated from the following equation: 

A (0.775) 100 

— * — rj —per cent causticity. 

In which: 

A = the number of grams per liter concentration of caustic soda (NaOH). 

B = the number of grams per liter concentration of total sodium oxide (Na^O). 



PRODUCING SODA PULP PROM ASPEN. 



57 



AUTOCLAVE TESTS ON ASPEN. 

A few autoclave tests on aspen (Populus tremuloides Michx.) were made in 1909. : 
The ordinary soda process was employed, but the digester used was a horizontal, rotary 
autoclave, made of 6-inch steel pipe, with a capacity of about 2 gallons. As the heat 
was furnished by Bunsen burners, there was no condensation or loss of liquid through 
overflow to modify the cooking conditions. Cooks were not blown, but the digester 
was quickly cooled to room temperature and then dumped. The pulps were thor- 
oughly washed with cold water and screened on a small diaphragm screen through 
slots of 0.006 inch width. The test material was cut from fairly young growth near 
Ridgeway, Colo. Portions of the logs tested, especially the centers and around knots, 
were discolored a dull reddish-brown, probably due to incipient fungous attack; other- 
wise the wood seemed to be sound. Chips were prepared in the manner described on 
page 15. Their sizes were five-eighths inch (with the grain) by three-sixteenths to 
one-fourth inch by one-half in^h to 6 inches (both across the grain). 

The data resulting from the tests are shown in Table 15. The column headings 
have the same significance as those in Tables 10 to 14, except as otherwise indicated. 
However, in the bleaching tests the standard color matched was that of bleached 
sulphite pulp, and, as soda poplar pulp in commercial operations is never bleached 
to so white a color, the test data should be reduced somewhat in estimating the com- 
mercial value for bleach required. The values for loss on bleaching also are probably 
a little greater on this account. 

The tests fall naturally into two groups. One of these consists of cooks 1, 2, and 4, 
in which the concentration of caustic soda in the cooking liquors was varied. The 
other consists of cooks 3 and 5, in which the duration at maximum pressure was the 
chief variable. Increases either of concentration or of duration resulted in decreases 
in the yield of pulp, loss on bleaching, and bleach required, except possibly in the 
case of one cook. All of the pulps produced were thoroughly cooked. The yields, as 
compared with those secured in the more recent tests (see Table 11), were uniformly 
very low and the losses on bleaching very high. The difference may be due to the 
methods and apparatus used or to deterioration of the wood from fungous attack, or to 
both. If the wood had been perfectly sound, it does not seem probable that the lower 
yields would have been accompanied by the higher amounts of bleach required and 
the larger losses on bleaching, even though these effects were slightly augmented by 
the higher standard of bleaching. 

Table 15. — -Cooking conditions and results of autoclave tests on aspen? 





Date of 
cook. 


Weight 

of chips 

charged 

(bone-dry 


Water 

in 
chips. 


Liquor charge. 


Initial 

volume of 

digester 

liquors 2 

per 
pound of 


Chemicals charged per 
100 pounds of chips 
(bone-dry basis). 


Cook 
No. 


Initial concentrations. 2 


Caus- 




















basis). 




NaOH. 


Na 2 C0 3 . 


Total 
Na 2 0. 


ticity. 


chips 

(bone-dry 

basis).' 


NaOH. 


Na 2 C0 3 . 


Total 
Na 2 0. 










Grams 


Grams 


Grams 














1909. 


Lbs. 


P.ct. 


per liter. 


per liter. 


per liter. 


P.ct. 


Galls. 


Lbs. 


Lbs. 


Lbs. 


1 


May 25 


1.652 


33.5 


80 


7.4 


66.3 


93.5 


0.375 


25.0 


2.3 


20.7 


2 


May 27 


1.652 


33.5 


50 


1.8 


39.8 


97.5 


.599 


25.0 


.9 


19.9 


3 


June 2 


1.652 


33.5 


90 


4.3 


72.3 


96.5 


.386 


29.0 


1.4 


23.3 


4 


June 8 


1.304 


18.3 


SO 


1.4 


24.1 


96.5 


1.000 


25.0 


1.2 


20.1 


5 


July 3 


1.920 


15.0 


90 


4.3 


72.3 


96.5 


.390 


29.3 


1.4 


23.5 



i These tests were made by Mr. Edwin Sutermeister, formerly in charge of the pulp-testing laboratory 
of the Forest Service at Washington, D. C. 
2 The water in the chips when charged is not taken into consideration. 



58 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

Table 15. — Cooking conditions and results of autoclave tests on aspen — Continued. 





Duration of cooking. 


Maxi- 
mum 
gauge 
pressure 

per 
square 
inch. 


Yields (bone-dry basis). 


Properties of unbleached 
pulps. 1 


Cook 
No. 


Total. 


At zero 
gauge 
pres- 
sure. 


At 
maxi- 
mum 
gauge 
pres- 
sure. 


Total 
crude 
pulp. 


Screen- 
ings. 


Screened 
pulp. 


Ash. 


Bleach 
required. 


Loss on 
bleach- 
ing. 


1 
2 
3 
4 
5 


Hrs. 
8.2 
8.5 
4.5 
8.0 
8.0 


Hrs. 
0.3 
.3 
.3 
.2 
.3 


Hrs. 

7.0 
7.0 

3.0 
7.0 
7.0 


Lbs. 

110 
110 
110 
110 
110 


P. ct. 
41.10 
44.23 
40.50 
46.97 
36.00 


P. ct. 
0.10 
.03 
.10 
.07 
.00 


P.ct. 
41.00 
44.20 
40.40 
46.90 
36.00 


P.ct. 

1.40 
1.27 
1.35 
1.25 
1.42 


P.ct. 
15.4 
14.7 
14.3 
15.8 
10.0 


P. ct. 
3.92 
4.08 
4.39 
4.68 
2.56 



(P. L.— 66— 1, S. 683.) 
1 The pulps produced were of good strength and of a fair degree of hardness; the color was very light 
reddish-brown. Shives were very few in number or almost absent. 



p manufacture. 
iquors at start of cook. 



Concentration of 
NaOH. 



eciftc gravity. I 



il,09 6 per cent l . 



( 2 ) 



i 1.03 2 per cent 1 (?)■ 



i 1.09 | 7 per cent 1 . 



1 1.08 I 7 percent, 
3 l. 06-1. 12 

11.08 ... 
il 09-1.11 6-9 per cent . 



I' 6-8 per cent... 
i."6 : /-i"i2 5-10 per cent 1 - 



( s ) 



il.07-l.ll 5-7 per cent Na 2 0. 



11.07 

11.09 ... 
il 09-1.11 7-9 per cent 1 - 
il 07-1.11 5-7 per cent 1 - 



and blowing, 45-60 minutes; total] 



Table lfi. — CooHng conditions employed in the soda process of wood-pulp manufacture. 





Practice followed. 


Digester. 


Quantity of chemicals charged. 


Quantity of cooking 
liquor charged. 


Cooking liquors at start of cook. 


Cooking 
pressure 

per 
square 
inch. 


Cooking 
tempera- 
ture. 


Durations of cooking. 


Blowing 
pressure 
per square 




No. 


Kind. 


Size. 


Wood 

capacity. 


Manner of heating. 


Actual caustic 
soda(NaOH). 


Total soda 
expressed as 
carbonate. 


Per cook. 


Per cord. 


Density. 


Concentration of 
NaOH. 


Caus- 
ticity. 


Total. 


From start 
tillcooking 
pressure is 
reached. 


At 
cooking 
pressure. 


Authority.* 




Baume\ 


Twaddle 


Specific gravity. 










Feet. 










Gallons. 


Gallons. 




18° 

(■) 


■ 1.09 
(') 




Per cent. 


Pounds. 

00 

90 

1SO-200 

ISO 

150-180 

65 or 

110 

90-110 

90-110 
100-120 

100-110 


°F. 


Hours. 


Hours. 


Hours. 


Pounds. 










:::::::. ::i:::::::::: 












(?) 












10-12 

0.5 or less. 










Cylindrical, 
vertical. 


stationary, 












60 per 
cwt. dry 
wood. 












Not blown. 






















10° 


1 1.03 












Houghton; Grininand Little, 
1891. 




Euro ractico(1870) 








336 lbs. per ton 
green wood. 














360-375 














Cylindrical, 
vertical. 


stationary, 


10 by 5 
27 by 7 


1 cord... 
4.3cords. 


Direct fire or steam 

jacket. 
Live steam 










■ 18° 

116° 
U2-21" 

'10° 
1 18-22° 

( s ) 


1 1.09 

11.08 
3 1. 00-1. 12 

■ 1.08 
1 1.09-1.11 

(') 







'93-W 
■ 8-10 






05 or more. 
■15 












- 3,400 


>705 










25-3 


7 


Congdon, 1880; Watt, 1907. 












<8-15°at60°F.. 
1,11° for poplar.. 
12-14° at 60° F. 

( s ) 




\ 














Cylindrical, 
vertical. 


stationary, 






Jacket, coils, or 

direct fire. 








More 

than 71)0. 
700 
























8-10 
0-10 

(*) 
































Cylindrical, 
vertical. 


stationary, 


27 by 7 


4.5 cords. 


Live steam 


■l50(?)-920 1bs. per 
cord. 1 


G35(?) t'i l.:*201hs. 
per cord. 1 


4,000- 
5,000 


'900- 
1,100 


10-15° at 60" F. 
(?) 


■ 11-21° 
( ! ) 


1 1.07-1.12 
( 5 ) 


5-10 percent J 


02-91 




■8i-13 


2J-3 
(•) 


75 










Technology, 1902. 
Clapperton. 1907. 
















800-950. lbs. per 
cord. 




























12-20 per cent of 
weight of wood. 








15-22° 

i 140 

■18° 

■ 18-22° 

1 15-22° 


1 1.07-1.11 

1 1.07 

U.09 

1 1.00-1.11 

il.07-l.ll 






130-160 

132-147 
88-118 
73-1 17 
73-1 70 
70-80 
100-130 
100-150 

125 


360 


•6 

>6 
'5-6 
•5-6 
8-9 














1 












































































































stationary or 








Live steam 




















































338-355 








Ik'vcridgo, 1911. 
























20° 


1 1.10 










0-8 

1-2 












8.5 cu. 

meters 

(=-sni)cu. 

ft.)' Of 

chips. 




637 kilos (=1,400 
lbs.) 1 Na 3 for 
charge. 




6,000 

liters 
(=1,321 
galls.)i 










353 








1911. 



































1 Calculated from other data given. 
•* Strong solution of caustic soda. 

<■ In add if ion in the lotal lime of coo kin 'j Congdon reports: 
— : t total dunfion or 



1 blowing, 45-00 minutes; total period for a cook, 11— 11 J hours. 



31001°— Bull. SO— 14. (To face page 58.) 



PRODUCING SODA PULP FROM ASPEN. 



59 






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PRODUCING SODA PULP PROM ASPEN. 61 

BIBLIOGRAPHY. 

(January, 1913.) 
PROPERTIES OF ASPEN AND ITS USE AS A PULPWOOD. 

Journal of the Society of Chemical Industry. Poplar wood pulp. In: Jr. 
Soc. Chem. Ind., 24 (1905), 148. 

L'Industria della Carta. Poplar and the paper industry. Extract in: Paper 
FQ911), (5), 13. 

Litchauer, Viktor. Die "amerikanische Aspenzellulose." 3 pp., illus. In: 
Zentrallblatt fur die oster.-ungar. Papierindustrie. XXIII (1905), (26), 822-5. 

Macmillan, H. R. Forest products of Canada: pulpwood. Bulletins 12 (1908); 
26 (1910); 30 (1911), Forestry Branch, Department of Interior, Canada. 9; 14; 17 
pp., tables, 8°. Ottawa; Government Printing Bureau, 1909; 1911; 1912. 

Papier Fabrikant. Die Pappel (Populus canadensis) als Papierholz. In: Papier 
Fabrikant, 9 (1911), 199-201. 

Sargent, Charles Sprague. Report on the forests of North America. Vol. IX, 
Reports of the Tenth Census, United States Department of the Interior, Census Office. 
612 pp., maps, tables, 4°. Washington: Government Printing Office, 1884. 

Svensk Pappers-Tidning. Poplar as a pulpwood in Italy. Swedish translation 
of an Italian letter. In: Svensk Pappers-Tidning, 12:te arg. (1909), (22), 225-6. 

United States — Agriculture, Department of — Forest Service — Bulletins 
74 and 77. Forests products of the United States, 1905; 1906. Wood used for pulp ; 
pulpwood consumption. 6; 8 pp., tables, 8°. Washington: Government Printing 
Office, 1907; 1908. 

United States — Commerce and Labor, Department of — Census, Bureau of — 
Forest Products No. 1. Pulpwood consumption: 1907; 1908; 1909; 1910. 14; 12; 
15; 10 pp., tables, 8°. Washington: Government Printing Office, 1908; 1909; 1911; 
1912. 

United States — Commerce and Labor, Department of — Census, Bureau of. 
Paper and wood pulp statistics; preliminary report for 1909. 6 pp., tables, 8°. Wash- 
ington, April 26, 1911. 

Weigle (W. G.) and Frothingham (E. H.). The aspens: their growth and man- 
agement. United States Department of Agriculture, Forest Service, Bulletin 93. 35 
pp., tables, 8°. Washington: Government Printing Office, 1911. 

THE SODA PROCESS OF PULP MAKING. 

Bersch, Joseph. Cellulose, Cellulose-produkte und Kautschuksurrogate. Berlin, 
1903. English translation, "Cellulose, cellulose products and artificial rubber" by 
Wm. T. Braunt. 336 pp., illus., 8°. Philadelphia: H. C. Baird and Co., 1904. 

Beveridge, James. Papermaker's pocketbook. 2d ed., 225 pp., illus., tables, 8°. 
London: McCorquodale and Co., Ltd., 1911. 

Clapperton, George. Practical papermaking. 2d ed., 226 pp., illus., 8°. 
London: Croxby, Lockwood and Son, 1907. 

Congdon, E. A. The manufacture of chemical fiber. In: School of Mines Quar- 
terly, X (1889), 163-172. 

Cross (C. F.) and Bevan (E. J.). Textbook of papermaking. 2d ed., 330 pp., 
illus., tables, 8°. London: E. & F.N. Spon, Ltd., 1900. 

Cross (C. F.), Bevan (E. J.), and Sindall (R. W.). Woodpulp and its uses. 270 
pp., illus., 8°. New York: D. Van Nostrand Co., 1911. 



62 BULLETIN 80, U. S. DEPARTMENT OF AGRICULTURE. 

De Cew, Judson A. The function of the caustic soda process in the production of 
cellulose from woods. In : Jr. Soc. Chem. Ind., 26 (1907), 561-3; Chemical Abstracts, 
1908, 319. 

Griffin (R. B.) and Little (A. D.). The chemistry of papermaking. 515 pp., 
illus., 8°. New York: Howard Lockwood and Co., 1894. 

Hofman, Karl. Praktisches Handbuch der Papier fabrikation. 2d ed., 2 vols., 
1800 pp., 4°. Berlin: Papier Zeitung, 1897. 

International Library of Technology, Vol. 20, Part 2. Manufacture of paper. 
58 pp., illus., tables, S°. Scranton, Pa.: International Textbook Co., 1902. 

Klein, Arthur. The process of manufacturing chemical wood pu.lp. Proceed- 
ings, Verein der Zellstol'f- und Papier- Chemiker, Berlin, 1909. Also in: Papier Zei- 
tung, 34, 227, 267: Chemical Abstracts, 1909, 1341. 

Leighton, Marshall Ora. Preliminary report on the pollution of Lake Cham- 
plain. United States Department of the Interior, Geological Survey, Water Supply 
and Irrigation Paper No. 121. 119 pp., illus., 8°. Washington: Government Printing 
Office, 1905. 

Paine, Jr., A. G. Description of the soda process as practiced at the mills of the 
New York and Pennsylvania Company, 1908. In: Vol. IV (pp. 2628-2633) of Pulp 
and Paper Investigation Hearings. United States House of Representatives, 60th 
Congress, 2d sess., Doc. 1502. Washington: Government Printing Office, 1909. 

Reid, T. Anderson. Wood as a papermaking material. Tables. In: Jour. Soc. 
Chem. Ind., 5 (1886), 273-276. 

Silcox, George W. Report on the art of printing and on manufactures of paper. 
With appendix, 30 pp., index, 8°. In: Vol. II, Reports of the Commissioners of the 
United States to the International Exhibition held at Vienna, 1873. United States 
Department of State. Washington: Government Printing Office, 1875. 

Sindall, R. W. The manufacture of paper. 275 pp., illus., bibl., 8°. New 
York: D. Van Nostrand Co., 1908. 

Sindall, R. W. Paper technology. 2d ed., 270 pp., illus., tables, 8°. London: 
Chas. Griffin and Co., 1910. 

Stevens, Henry P. Paper mill chemist, 280 pp., 67 illus., 82 tables, 8°. Lon- 
don: Scott, Greenwood and Son, 1908. 

Stjtermeister, Edwin. The soda process for cellulose manufacture; the consump- 
tion of caustic soda and its influence on yield and bleaching properties. (Presented 
at the Eighth International Congress of Applied Chemistry in New York, Sept. 11, 
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Watt, Alexander. The art of papermaking. 3d ed., 260 pp., illus., 8°. Lon- 
don: Crosby, Lockwood and Son, 1907. 

EFFECTS OF CAUSTIC SODA AND WATER ON CELLULOSE. 

Cross (C. F.) and Bevan (E. J.). Cellulose. 3d ed., 328 pp., plates, diag., tables, 
8°. New York: Longmans, Green and Co., 1903. 

Cross (C. F.) and Bevan (E. J.). Researches on cellulose, 1895-1900, 2d ed., 180 
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Miller, O. Constitution of soda cellulose. In: Berichte, 41, 4297-4304; Chemi- 
cal Abstracts, 1909, 650. 



PEODUCING SODA PULP FROM ASPEN. 63 

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1911, 1838. 

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atures in presence of water," in: Jour. Soc. Chem. Ind., 8 (1889), 913. 

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Chemical Abstracts, 1908, 3403. 

o 





Contribution from the Bureau of Plant Industry, Wra. A. Taylor, Chief, and 
the Federal Horticultural Board, C. L. Marlatt, Chairman. 

March 31, 1914. . 

THE POTATO QUARANTINE AND THE AMERICAN POTATO 

INDUSTRY. 

By W. A. Orton, 

Pathologist in Charge of Cotton and Truck Disease and Sugar-Plant Investigations, 
Bureau of Plant Industry, and Vice Chairman of the Federal Horticultural Board. 

INTRODUCTION. 

In September, 1912, a quarantine order was issued by the Secre- 
tary of Agriculture prohibiting the importation of potatoes into the 
United States from the British Isles, Germany, Austria-Hungary, 
and from Newfoundland, St. Pierre, and Miquelon, on account of the 
potato wart. In December, 1913, an additional temporary quar- 
antine was laid against Canada and all the countries of Europe, 
pending further investigations of the occurrence of powdery scab 
and the establishment of a system of inspection on the part of for- 
eign governments that will provide for the certification of potatoes 
offered for export to the United States, to the effect that they are free 
from disease, that they were grown in a disease-free locality from 
which the American quarantine has been lifted, and that in other re- 
spects they conform to the regulations established by this Government. 

The discussion of these quarantines has focused public attention 
on the potato question to an unusual degree and has emphasized 
the need for available information concerning the reasons for the 
quarantines, the nature of the new regulations, and the general 
status of the potato industry. This bulletin is intended as a contribu- 
tion to this end. It is sought also to outline a constructive policy 
for future development that will lessen losses from disease and other 
wastes and place potato culture on a basis more profitable to the 
producer, while at the same time permanently reducing the cost to the 
consumer of this staple food. 

Note. — This bulletin tells of the necessity for establishing a quarantine against potatoes from certain 
countries, gives brief descriptions of the potato diseases that have been imported, indicates some of the 
agencies by which these diseases have been spread over this country, and gives information that potato 
growers should have in advance of the planting season. It is intended for general distribution. 

30952°— Bull. 81—14 1 



2 BULLETIN 81, I T . S. DEPARTMENT OF AGRICULTURE. 

REVIEW OF THE POTATO-DISEASE SITUATION. 

TYL.cn seeking' protection from new plant diseases we must be 
guided by past experience and by our knowledge of the general 
principles controlling the occurrence and spread of plant parasites. 
It is evident that agriculture in general bears a burden that increases 
from year to year as new diseases or insect enemies appear. In 
colonial limes and up to 1840 the potato seems to have been free 
from many serious pests that have come in since. We now list IS 
or 20 diseases, not including insects, that attack potatoes in some 
part of the United States. The yearly loss from them is difficult to 
estimate, but the injury from tuber rots and related troubles was 
recently placed by the Department of Agriculture at over $30,000,000 
annually, and diseases which attack the crop in the field probably 
reduce the value of the harvest by another $30,000,000 per annum. 

Not only do new parasites appear at frequent intervals, but they 
can rarely, if ever, be exterminated. A plant disease, once estab- 
lished here, is likely to be with us forever. Under these circumstances 
it is to the credit of American farmers that they havs, during the 
last generation, by the adoption of scientific methods of fertilization 
and culture and by spraying and seed treatment for diseases, main- 
tained the average yield per acre of the country and in the more 
progressive sections considerably increased it. On the other hand, 
the average yield is still only about half what it might be, as judged 
by European standards, and the cost of spraying, increased ferti- 
lizers, etc, constitutes a heavy annual tax on the grower. 

INTRODUCED PARASITES THE MORE DANGEROUS. 

Plant parasites may be divided into two classes, those endemic or 
native to the country and those introduced from other countries. 
It is a general principle, fully established by experience, that parasites 
introduced from other continents or distant parts of the same 
continent are more injurious than the native parasites of the same 
crop and more virulent and destructive in their new habitat than 
they had been at home. 

The United States has had many costly examples of this fact, 
among which may be cited the gipsy moth, the brown-tail moth, the 
codling moth, the asparagus rust, the hollyhock rust, and that recent 
immigrant from the Orient, the chestnut bark disease, which is 
threatening to destroy our chestnut forests. 

Several potato diseases are of foreign origin. The examples men- 
tioned below are of special interest. 

LATE-BLIGHT. 

I]i the period from 1830 to 1842 there was introduced into both 
Europe and America a new potato disease which causes a blighting 
of the foliage, followed by decay of the tubers. This disease, called 



THE POTATO QUARANTINE. 8 

late-blight, is worst in moist, not too hot, weather, when it may 
spread with incredible rapidity, ruining the most vigorous field in 
three or four days. The same fungus spreads to the tubers, pro- 
ducing a typical dry rot in dry storage, which may become a wet 
rot in damp soil through bacterial action. The cause of this disease 
is the late-blight fungus (Phytophthora infestans), and its original 
habitat is believed to be South America. It gained headway soon 
after its introduction, and in 1845 nearly destroyed the potato crop 
of Europe, especially in Ireland, and did much injury in America. 
It has been present every year since to a greater or less extent, and 
serious outbreaks have recurred periodically when weather conditions 
favored its development. In North America it is most serious in the 
northeastern part of the United States and the adjacent provinces of 
Canada. Thorough spraying with Bordeaux mixture will control it, 
but the losses are nevertheless still large. There is no hope of the 
extermination of this disease. Potato growers will always have it 
to reckon with. 1 

BLACK-LEG. 

A disease marked by the blackening and shriveling or softening of 
the base of the stalk, a typical curling and yellowing of the foliage, 
and in late cases by an infection and partial decay of the tuber has 
been introduced from Europe comparatively recently, probably 
having come first to Canada and thence to Maine. It is a bacterial 
trouble, 2 transmitted in the seed potatoes. Two points are of 
special interest: (1) The widespread distribution it has secured 
within a few years, because seed potatoes are shipped from the 
district which was the original center of infection to nearly every 
State in the Union; (2) black-leg takes on a more virulent form 
under southern conditions and may destroy 10 to 75 per cent of a 
crop in Virginia when the seed farm in the North had much less of it. 

Rigid methods of seed selection and seed treatment will control 
the disease, and these must be insisted upon. 3 

SELVES SCUEF. 

An example of the rapid spread of an imported fungus is afforded 
by the silver scurf (Spondylocladium atrovvrens) . This is a superficial 
parasite of the potato tuber, beginning as a brown mold on the 
surface. Later the infected areas take on a glistening silvery gray 
color, and finally the tubers shrivel more or less, due to loss of 

1 A complete description of the late-blight has been, given by Jones, Gidd ings, and Lutman, in " Investiga- 
tions of the potato fungus Phytophthora infestans," TJ. S. Department of Agriculture, Bureau of Plant 
Industry, Bulletin 245, IG12. Obtainable from the Superintendent of Documents, Government Printing 
Office, for 30 cents. 

2 Bacillus -phytopliiliorUG Appcl and related forms. 

s The reader desiring more information on black-leg is advised to procure Bulletin 174 of the Maine 
Agricultural Experiment Station, Orono, Me. 



4 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

moisture. Silver scurf has been known in Europe for many years, 
but it was not noticed in America, except in one instance (by Dr. 
Clinton in Connecticut in 1907), until 1912, when it appeared on 
potatoes from nearly every State from Maine to Florida and westward 
to Wisconsin. It is now thoroughly established here and, though a 
minor trouble, adds another to the agencies which disfigure potatoes. 
There is evidence to justify the fear that silver scurf may become 
more injurious in the United States than it has been in Europe. 1 

Other potato parasites have come from the far West or from the 
South. The migration of the Colorado potato beetle from the Rocky 
Mountain region is well known. Two diseases, the southern bacterial 
brown-rot and the Fusarium wilt, appear to be of southern, possibly 
tropical, origin, though this is not fully established. 

THE WART DISEASE. 

Potato wart, black scab, or canker is a disease which transforms 
the tubers into irregular, warty excrescences, at first greenish or 
white, then black and decaying. It is a fungous disease (Synclii- 
triura endolioticum) of comparatively recent discovery, first described 
from Hungary in 1896 and found in England about 1902 and in 
Westphalia in Germany in 1908. It has spread considerably during 
the past decade until it seems firmly established in England and 
Scotland, has gamed a foothold on the coast of Ireland, and has 
crossed the Atlantic to Newfoundland, where Dr. H. T. Giissow, 
Dominion botanist, discovered it in 1909. Fortunately, it has not 
yet been found on potatoes grown in the United States. 

Most authorities consider it one of the very serious diseases of the 
potato, as it converts the tuber into an ugly, irregular, and utterly 
worthless article, and when established in the soil will attack the 
succeeding crops and prevent the growing of potatoes hi such in- 
fected soil for many years. 

The countries where the wart occurs have for the most part taken 
vigorous measures to suppress it, and other nations have endeavored 
to prevent its introduction. It was primarily on account of this 
trouble that the Secretary of Agriculture issued Quarantine Order 
No. 3, September 20, 1912, prohibiting the entry of potatoes into the 
United States from Newfoundland, the islands of St. Pierre and 
Miquelon, the United Kingdom (including England, Scotland, Wales, 
and Ireland), Germany, and Austria-Hungary, although powdery 
scab was also taken into consideration at that time. 2 

' For further details, see the paper in Circular 127, Bureau of Plant Industry, U. S. Department of 
Agriculture, by I. E. Melhos, entitled "Silver scurf, a disease of the potato." Obtainable from the Super- 
intendent of Documents, Government Printing Office, for 5 cents. 

'' for I . i formation on the wart disease, see Farmers' Bulletin 489. 



THE POTATO QUARANTINE. 5 

POWDERY SCAB. 

Powdery scab is a tuber trouble, differing from the common scab 
mainly in the following particulars :* The scab spots, or sori, are more 
often circular and not usually as great in diameter as those of the 
common (Oospora) scab. They first appear as discolored, slightly 
raised spots covered by the epidermis, which later breaks away, leav- 
ing a pit, filled at maturity with a brownish dust, the spore balls of the 
parasite. With powdery scab there is less of a corky layer formed 
under the spot than is the case with common scab. For this reason 
there is a loss of moisture in storage and the eventual formation of a 
depressed spot. In severe attacks of powdery scab there is a can- 
kerous stage or eating away of the tuber, which nearly or quite de- 
stroys its value. Finally, there is a great difference between the 
organisms which cause the two kinds of scab. Common scab is due 
to a parasite (Oospora scabies) of very minute, threadlike form, now 
considered to be more related to the bacteria than to the filamentous 
fungi. Powdery scab is due to a slime mold (Spongospora subter- 
ranea), a relative of the cabbage clubroot organism. Its spore balls 
appear under the microscope as large balls characteristically marked 
and easily recognized. 

Osborn holds that the soil moisture determines to a great extent 
the damage done by the disease. Under dry conditions of the soil the 
external appearance is limited to small circular patches about 5 mm. 
across. Under wet conditions the damage is more serious and the 
scabs may be as large as 3 to 4 cm. in diameter and as much as 2 cm. 
in depth. 

Powdery scab is common in northern Europe, where it has been 
known for many years. In Canada it occurs in the provinces of New 
Brunswick, Prince Edward Island, Nova Scotia, and Quebec, not 
universally but rather generally distributed in many sections. The 
disease appears not to be established in the United States except in 
isolated cases, mostly near the Canadian border, where further sur- 
veys are now being made. There is need for the continuance of 
careful surveys in all States where any imported potatoes may have 
been planted, to insure the stamping out of any infection that may be 
present. 

POWDERY SCAB IN IMPORTED POTATOES. 

Very little is known of the extent to which powdery scab was pres- 
ent in potatoes brought from Europe prior to 1912. In October, 1913, 
in response to market demands, large shipments of potatoes began to 
come in from the Netherlands, Belgium, and Denmark, as well as 
from Canada. Examinations of these potatoes at the ports of New 

i Cf. Melhus, I. E., Powdery scab (Spongospora subterranea) of potatoes, IT. S. Department of Agriculture, 
Bulletin 82, 191-1. This publication contains a full description of the disease and the causal parasite. 



6 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

York and Boston by departmental inspectors showed the presence of 
powdery scab in most of the arrivals from the Netherlands and in 
many of those from Belgium and Canada. The percentage of pow- 
dery scab varied from a trace up to 20 per cent or more. The scab 
was usually of the superficial type, though some advanced cases were 
found. Common scab was also present. 

It has been suggested since by the representatives of the Govern- 
ments of the Netherlands and Belgium that these infected potatoes 
may have originated in Germany rather than in their countries, and 
an examination of the situation has indicated that the original quar- 
antine order may not have provided sufficient safeguards against the 
transshipment of potatoes from Germany and other quarantined 
countries through Antwerp, Rotterdam, and other nonquarantined 
ports. 

In the situation thus presented, the Department of Agriculture 
had to determine promptly two points: (1) Is there danger that 
diseases present on imported potatoes will become established in 
American fields? (2) Is the powdery scab a new and dangerous 
disease requiring exclusion by quarantine ? 

POSSIBLE INFECTION FROM IMPORTED POTATOES. 

The greater portion of the foreign potatoes imported are intended 
for table purposes and are consumed in New York, Boston, and Phila- 
delphia, where it has been urged that by no possibility could infection 
reach potato fields. The facts, as determined by the Department of 
Agriculture, are that hundreds of thousands of bushels have been 
shipped from New York to interior points and that foreign potatoes 
have been sold as far west as St. Louis and as far south as New 
Orleans. This was particularly the case in 1911. There are abun- 
dant opportunities for disease germs on potatoes used for food to 
reach the land. Partially decayed or scabby tubers are sorted out 
by the retailers and disposed of for feeding to five stock, and manure 
thus infected is hauled to surrounding farms. Parings from the 
potatoes go into the family garbage can and find their way directly 
or indirectly to cultivated fields. 

A second avenue of infection is through the use of foreign potatoes 
for seed. It is now fairly well known that European varieties do not 
succeed in the United States and that the use of foreign seed is not 
profitable, yet the number of actual instances traced by the Depart- 
ment of Agriculture where European seed potatoes were purposely 
planted as an experiment or through ignorance of their lack of value, 
or where unscrupulous dealers had sold foreign stock as domestic, is 
large enough to show that the danger from this source is a real one. 
Canadian potatoes are valued for seed purposes and were being 
bought in large quantities when the quarantine was laid. 



THE POTATO QUARANTINE. 7 

The use of foreign sacks which, had contained infected potatoes 
is a third means of spreading disease to American potatoes. Great 
numbers of these sacks are gathered up through secondhand dealers 
and sold in New York, Maine, and other producing centers for use in 
shipping domestic potatoes. It has not been the practice to sterilize 
these sacks, though a treatment with steam would render them safe. 

The conclusion reached after consideration of the possibility of the 
spread of disease through garbage, seed potatoes, and reused sacks 
was that it will be impossible to prevent the permanent establishment 
in the United States of any parasitic disease common on imported 
potatoes. 

IS THE POWDERY SCAB DANGEROUS? 

The Federal Horticultural Board was compelled to decide promptly 
whether the best policy for the country would be to treat powdery 
scab as a disease of minor importance and make no restrictions on 
importations from infected countries, recognizing as inevitable that 
the disease would soon become common and widely distributed in the 
United States, or whether it should be considered sufficiently danger- 
ous to warrant exclusion measures. In deciding this important 
point all available information was secured. Advice was sought 
from the plant pathologists in the several State experiment stations, 
all foreign publications on the subject were consulted, and the advice 
of representatives of foreign governments was taken through corre- 
spondence and at a public hearing held in conformity with the plant 
quarantine act on December 18, 1913. This hearing was attended 
by a large number of plant pathologists and other State officials, by 
representatives of farmers' organizations and commercial bodies, and 
by interested individuals. The thousands of letters, petitions, and tele- 
grams received by the board showed that the potato growers of the 
country are no longer apathetic on the question of potato diseases. 

The advice of the foreign representatives was to the general effect 
that European potatoes had been imported in large quantities for 
many years; consequently, that if powdery scab were communicable 
it must be common in the United States, but overlooked, in which 
event a quarantine would not be lawful under the plant quarantine 
act. Further, that if powdery scab had not already become estab- 
lished, this fact should be considered as evidence that no danger 
exists. 

It was also represented that powdery scab is a disease of such 
minor importance that the interruption of trade by a quarantine 
was not justified, and that, if introduced, it could be controlled by 
using no infected tubers for planting and by discontinuing the use of 
infected land for growing potatoes. The evidence on each of these 
points and on other phases considered is summarized later. 



8 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

OCCURRENCE IN THE UNITED STATES. 

During the past two years the pathologists of the Department of 
Agriculture have visited every important jDotato section to look for 
powdery scab and other diseases. Potatoes in the large markets have 
been examined, the Plant-Disease Survey collaborators in the several 
States have been asked to be on the watch for powdery scab, and 
the State of Maine has been given special attention by both the 
department and the State experiment station. 

Outside of the State of Maine no definite cases have been traced to 
farms, but some evidence of powdery-scab infection was found by 
Dr. Morse, of the Maine experiment station, in two sendings of pota- 
toes from western Nebraska and Massachusetts. 

Considerable powdery scab has been found in Maine very recently. 
This infection is most abundant on the northern border of Aroostook 
County, but scattered cases occur elsewhere, many of which have 
been traced directly to seed potatoes brought over from the infected 
districts of Canada. Thus far only a very small percentage of Maine 
farms has been found infected. 

The State authorities have taken prompt and vigorous action to 
survey the State in order to locate all infections. An inspection 
service has been organized, which will issue certificates of freedom 
from powdery scab, and no potatoes known to be diseased will be 
allowed to leave the State. Seed stock will be examined with special 
care. 

It is believed that these measures will provide an adequate safe- 
guard against the future spread of powdery scab to other States. 
The State of Maine expects to quarantine all infected fields and will 
endeavor to stamp out the disease. 

A more thorough survey of other States is now under way. The 
evidence is veiy strong that at the present time powdery scab is not 
"widely distributed in the United States." 

LIKELIHOOD OF SPREAD. 

That the disease has not already gained a greater foothold in spite 
of numerous importations is perhaps the strongest argument advanced 
by the opponents of a quarantine. This is probably a matter of 
good fortune rather than proof of noncommunicability. The con- 
trary evidence includes its apparent general occurrence in certain 
foreign districts, the fact reported by Dr. Melhus that in Canada 
those sections which use European varieties and which often import 
seed are more infected than those using seed from American sources, 
and the experimental evidence secured by Dr. Morse in Maine and 
by Irish workers that the disease is readily communicable by planting 
infected seed potatoes. 



THE POTATO QUARANTINE. 9 

RELATIVE IMPORTANCE IN EUROPE AND THE UNITED STATES. 

Powdery scab has been in the past a minor potato disease in 
Europe; that is to say, it has not been recognized by the public as a 
serious trouble, nor has it engaged the time and attention of scientific 
investigators to the extent that other potato diseases, such as leaf- 
roll, have. Recent publications by Johnson and by Pethybridge, the 
leading plant pathologists of Ireland, lead to the conclusion that the 
disease is more serious there than has previously been realized, par- 
ticularly in gardens and fields continuously cropped in potatoes, 
where it tends to assume the cankerous stage and reduces the market 
value of the potatoes for eating purposes. It may well be that 
powdery scab is becoming more serious in Europe. Johnson states: 

I have no doubt myself that Spongospora scab has a good deal to do with the miser- 
able average yield per acre of potatoes in the west of Ireland. * * * It is in some 
districts of Ireland as injurious to potatoes as finger-and-toe is to turnips. 

DIFFERENCES IN MARKET STANDARDS. 

An important consideration in this connection is that any scab or 
other disfigurement of the tuber reduces its market value much more 
in the United States than in Europe. The consumer abroad does 
not object seriously to a scabby potato. In fact, we are assured by 
our English visitors that it is a general belief in Great Britain that 
scab is an indication of good quality for eating purposes. In the 
United States, however, scabby potatoes are rejected for market pur- 
poses. In Maine they were sorted out and sold to the starch factory 
for 50 cents per barrel as compared with $1.50 which they would 
have brought if clean. In communities where there are no starch 
factories the scabby potatoes are fed to stock or left lying in the 
field. As a consequence, scab-infected fields are worthless for potato 
growing and their market value is greatly impaired. 

SCAB DISEASES WORSE IN THE UNITED STATES THAN IN EUROPE. 

Powdery scab has not occurred in the United States to an extent 
that permits any comparison of its virulence here with its behavior 
in Europe. It is, however, a well-known fact that introduced 
troubles as a class are more destructive than in the country of origin, 
owing to differences in climate or other conditions. The several im- 
portant potato districts of the United States — Maine, New York, the 
trucking districts of the Atlantic seaboard, the northern Great Lake 
district, the Red River Valley, Colorado, Idaho, Oregon, California, 
etc.— differ exceedingly in soil and climate, and there is reason to fear 
that powdery scab might find in one or several of these districts con- 
ditions much more favorable than exist in Europe and that it would 
assume a more virulent for jr.. 
30952°— Bull. 81—14 2 



10 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

It is certain that our common scab is much more common and 
disfiguring throughout the United States than it is in Europe, and 
the injuries caused b} 7 the fungus Rhizoctonia to potatoes in the West 
are greater than any reported from Europe. 

COMPARISON OF POWDERY-SCAB INJURIES. 

Common scab produces a roughened spot or pockmark on the 
tuber, which in its worst stage may cover the whole potato. Under- 
neath the scab spots, however, a cork layer is formed and the potato 
remains sound. It is not more subject to decay than other potatoes, 
and the actual injury from a food standpoint is due to the greater 
loss in peeling before cooking. 

Powdery scab in its milder form causes no greater outward disfigu- 
ration than common scab, but there is less of a cork layer formed 
and a progressive decay frequently follows. The cankerous stage of 
powdery scab is more objectionable than any phase of common scab 
and is as bad as the wart disease. Finally, no means of controlling 
powdery scab through the disinfection of seed potatoes, as practiced 
for common scab, has proved wholly satisfactory. 

All these considerations led the Department of Agriculture to the 
conclusion that measures for preventing the introduction of powdery 
scab into the United States were not only fully justified, but were 
demanded by every rule of prudence and precaution. 

Most foreign countries have long since wisely adopted a similar 
procedure with reference to American potatoes, mainly on account 
of the Colorado potato beetle. Canada maintains a complete em- 
bargo against all European countries, and most of the English 
colonies restrict the importation of potatoes to a greater or less extent 
on account of the wart disease and other troubles. 

OTHER REASONS FOR POTATO REGULATIONS. 

Experience gained in the enforcement of the potato quarantine 
order of September 20, 1912, and further investigations of potato 
diseases and insect enemies have shown that more efficient and log- 
ical means are required for the adequate protection of this country 
against the potato parasites of the world. 

Where a quarantine is laid against a whole country on account of 
an infection limited to a small portion of that country, the justice 
of the act is questioned by residents of the disease-free districts, yet 
there has been no means of limiting quarantines by other than national 
boundaries except through the active cooperation of the foreign 
government. 

Where a quarantine is laid against one country and not against 
another concerning a commodity like potatoes, which is a staple ar- 



THE POTATO QUARANTINE. 11 

tide of trade between the two nations, it is very difficult to prevent 
transshipments from the quarantined country through the ports of 
the nonquarantmed country unless special measures are taken by 
the governments concerned to regulate such trade. 

Finally, it is impossible to foresee all the conditions that will arise 
in the course of international commerce. Shipments come from new 
sources and may bring parasites hitherto unknown to which existing 
regulations may not apply. An example is afforded by some small 
importations of potatoes from South America in 1913, which were 
found infested with new species of weevils, more dangerous than any 
previously known, which tunnel through the tuber and destroy its 
value without greatly impairing its appearance. 1 This finding em- 
phasizes the necessity of maintaining a careful watch over all pota- 
toes coming from South or Central American sources. Effective 
regulations are therefore to be preferred to quarantines, in order to 
permit the most complete protection against the introduction of 
parasites without hampering trade more than is necessary. 

A step in this direction has been taken by the issuance of the fol- 
lowing order applying to potatoes the provisions of the nursery stock 
regulations, under the plant quarantine act: 

United States Department op Agriculture, 

Opfice op the Secretary, 
Federal Horticultural Board. 

Order Covering Admission of Foreign Potatoes under Restriction. 

The Secretary of Agriculture has determined that the unrestricted importation 
from any foreign country of the common or Irish potato grown in the Dominion of 
Canada, Newfoundland, Great Britain, Ireland, Continental Europe, and other foreign 
countries may result in the entry into the United States, its Territories and Districts, 
of injurious potato diseases, including the powdery scab (Spongospora nibterranea) , 
and injurious insect pests. 

Now, therefore, I, David F. Houston, Secretary of Agriculture, under authority 
conferred by section 5 of the act of Congress approved August 20, 1912, known as 
''The Plant Quarantine Act" (37 United States Statutes at Large, page 315), do 
hereby determine and declare that on and after January 15, 1914, common or Irish 
potatoes imported or offered for import into the United States or any of its Territories 
or Districts shall be subject to all the provisions of sections 1, 2, 3, and 4 of said act of 
Congress. 

Done at Washington this 22d day of December, 1913. 

Witness my hand and the seal of the United States Department of Agriculture. 

[seal.] David F. Houston, 

Secretary of Agriculture. 

■ ' Pierce, W. Dwight. Journal of Agricultural Research, vol. 1, no. 4, p. 347-352, pi. 3, 1914. 



12 BULLETIN 81 7 U. S. DEPARTMENT OE AGRICULTURE. 

Pending the completion of arrangements with foreign governments 
for the survey and delimitation of disease-free districts and for the 
inauguration of a system of inspection and certification of potatoes, 
a temporary quarantine was laid, as follows: 

United States Department of Agriculture, 

Office of the Secretary, 
Federal Horticultural Board. 

Notice of Quarantine No. II (Foreign), 
potato quarantine. 

The fact lias been determined by the Secretary of Agriculture that injurious potato 
diseases, including the powdery scab {Spongospora subterranea), new to and not 
heretofore widely prevalent or distributed within and throughout the United States, 
exist in the Dominion of Canada, Newfoundland, the islands of St. Pierre and Mique- 
lon, Great Britain, Ireland, and Continental Europe, and are coming to the United 
States with imported potatoes. 

Now, therefore, I, David F. Houston, Secretary of Agriculture, under the authority 
conferred by section 7 of the act of Congress approved August 20, 1912, known as 
"The Plant Quarantine Act" (37 United States Statutes at Large, page 315), do hereby 
declare that it is necessary, in order to prevent the introduction into the United 
States of such potato diseases, to forbid the importation into the United States, from 
the countries hereinbefore named, of the common or Irish potato {Solarium tuberosum) 
until such time as it shall have been ascertained, to the satisfaction of the Secretary 
of Agriculture, that the country or locality from which potatoes are offered for import 
is free from such potato diseases. 

On and after December 24, 1913, and until further notice, by virtue of said section 
7 of the act of Congress approved August 20, 1912, the importation, from the countries 
hereinbefore named, of the common or Irish potato, except for experimental or scien- 
tific purposes by the Department of Agriculture, is prohibited: Provided, That ship- 
ments of such potatoes loaded prior to December 24, 1913, as shown by consular in- 
voices, will be permitted entry up to and including January 15, 1914. 

Done at Washington this 22d day of December, 1913. 

"Witness my hand and the seal of the United States Department of Agriculture. 

[seal.] David F. Houston, 

Secretary of Agriculture. 

A GENERAL QUARANTINE NOW IN EFFECT. 

The order quoted above has resulted in the stoppage of potato 
importations from Canada and all the countries of Europe for an 
indefinite period. It is not known at present how many of these 
countries will ultimately qualify for the lifting of the quarantine, but 
the apparent general distribution of powdery scab in many of them 
makes it improbable that they will resume shipments to the United 
States in the near future. Certain portions of Canada are reported 
to be nearly free from powdery scab, and the vigorous campaign now 
being waged there against the disease offers hope that the restriction 
may be modified with respect to specified districts at an early date. 

The initiative in lifting the quarantine rests with the foreign 
government, which must notify the United States that specified dis- 



THE POTATO QUARANTINE. 13 

tricts have been surveyed and found to be free from wart and powdery- 
scab and that they are ready to inspect and certify potatoes intended 
for export, in conformity with our regulations. 

Such action has now been taken by the Kingdoms of Belgium and 
Denmark, and on February 20, 1914, the quarantine was lifted 
from these countries by an order of the Secretary of Agriculture, 
and hereafter their potatoes may be imported into the United States 
subject to and in accordance with the general regulations referred to. 
These regulations have been issued in printed form, and all persons 
desiring full details, especially as to the procedure to be followed in 
making importations, should procure an official copy. 1 

GENERAL EXPLANATION OF REGULATIONS. 

Control of importations is secured through a system of permits, as 
already in force for nursery stock. The importer makes his applica- 
tion to the Federal Horticultural Board at Washington, on forms 
provided, and receives a permit authorizing him to import potatoes 
from a specified firm and district from the time of issuance until 
June 30 following. A permit for each shipment is not required. 
Notice must be given to the board when each shipment arrives. For 
details, the regulations should be consulted. 

IMPORTATIONS ALLOWED FROM DISEASE-FREE DISTRICTS ONLY. 

The regulations provide that before the quarantine is lifted or 
permits are granted for importations from any country the officials 
of that country shall determine by a field survey, or in the case of 
the present crop by a cellar or pit inspection, that the country or 
district is entirely free from wart and powdery scab. 

It is not intended that there shall be any attempt made to sepa- 
rate by sorting the clean from the infected potatoes. The warning 
has been emphatic from all pathologists consulted that such an 
inspection would be utterly impracticable; that if any disease was 
present in a lot of potatoes it would be out of the question to sort 
them under commercial conditions without overlooking some disease. 
Infection might also be carried on healthy potatoes that had been in 
contact with diseased tubers. 

It is believed by the Federal Horticultural Board that the freedom 
of a district from disea.se can be determined with sufficient accuracy 
to afford a reasonable safeguard when checked by the foreign inspec- 
tion and by inspection on arrival at the port of entry. 

Prevention of transshipments from quarantined districts is accom- 
plished through the cooperation of the foreign government, which 
must provide an ' l effective quarantine ' ' against districts quarantined 

1 Regulations governing the importation of potatoes into the United States under the provisions of the 
order of the Secretary of Agriculture issued December 22, 1913. 



14 BULLETIN 81, Lf. S. DEPARTMENT OF AGRICULTURE. 

by the United States. This may be done by a decree prohibiting the 
exportation to the United States of potatoes not grown in the country 
taking the action. 

CERTIFICATE OF INSPECTION. 

No potatoes are to be admitted to the United States under the new 
regulations unless they are accompanied by a certificate issued by an 
official authorized of the country of origin, stating that they were 
grown in a specified disease-free district or locality, that they have 
been inspected by him and found free from dangerous insects and 
plant diseases, and that they are packed in containers that have 
never been used for potatoes. An original certificate of this nature 
must accompany the invoice when presented at the customs office, 
and a copy of the certificate must be attached to each sack, barrel, 
or other container. Provision is made for bulk carload shipments, 
but not as yet for wagonloads hauled across the border. 

INSPECTION ON ARRIVAL. 

Shipments will not be released from customs until inspected by a 
representative of the Federal Horticultural Board and found free from 
dangerous diseases. If powdery scab or wart is discovered the ship- 
ment must be exported or destroyed. 

The most important safeguard provided is the limitation of imports 
to potatoes grown hi disease-free districts or countries and the foreign 
inspection and certification. The port of entry inspection in the 
United States serves as a check on these, but is not a sufficient means 
in itself, for the reasons already stated and because only a portion of 
each shipment can be carefully looked over without maintaining an 
army of inspectors. 

LIMITATION OF PORTS OF ENTRY. 

The right is reserved under the new regulations to restrict importa- 
tions of potatoes to ports of entry named by the Federal Horticultural 
Board when the permit is granted. It is manifestly impossible to 
maintain an inspection service at each customs office, and at the out- 
set it is probable that entries will be allowed regularly only at New 
York and Boston, with the exception of special cases where it proves 
feasible to have inspections made elsewhere. By far the greater part 
of the potatoes imported in past years have come to the port of New 
York. Permits must be secured in advance of importation in all 
cas( s. 

ADDITIONAL SAFEGUARDS. 

If inspection at the port of entry shows that potatoes are infected 
with the wart disease or with powdery scab or other injurious plant 
diseases, or with injurious insect pests, the shipments will be refused 



THE POTATO QUARANTINE. 15 

entry. Permits for the entry of potatoes niay be refused and existing 
permits may be canceled on proof that the certificate of inspection 
does not correctly give the locality where the potatoes were grown, 
the character of the shipment as to freedom from disease or insect 
infestation, or falsely states that the containers have not been previ- 
ously used for the shipment of potatoes. 

Permits may be canceled and further permits refused for the impor- 
tation of potatoes from any country whenever such potatoes, in the 
judgment of the Federal Horticultural Board, are found to be so in- 
fected as to indicate plainly that the foreign inspection is merely 
perfunctory, or if the permittee fails to give to the Secretary of Agri- 
culture and to the duly-authorized inspector of the department at 
the port of entry designated in the permit notices of the arrival of 
potatoes or gives a false notice. 

IMPORTATIONS FEOM NONQUARANTINED COUNTRIES. 

Potatoes will be allowed to enter from sources other than Canada 
and the countries of Europe when properly inspected and certified by 
the authorized officials of the country of origin. The importers 
must comply with the permit requirements already mentioned. 

Bermuda has complied fully with the regulations by prohibiting 
the importation of potatoes from Canada and Europe and by inaug- 
urating a rigid inspection service. The importation of potatoes 
from these islands has therefore continued without check. 

The total quantity of potatoes brought from Bermuda during the 
year ended June 30, 1913, was 141,422 bushels. These are all en- 
tered at New York and find a special market at a high price. None 
are used for planting in the United States. 

The importation of potatoes from the State of Chihuahua, in 
Mexico, having been determined by an inspector of the Department 
of Agriculture to be attended by no risk from insects or diseases, the 
requirement of foreign certification has been waived temporarily in 
consideration of existing conditions in Mexico, and permits are being 
granted for such importations, from Chihuahua only, subject to in- 
spection at El Paso, Tex., the port of entry. 

Last year's importations from Mexico amounted to 8,301 bushels. 

RELATION OF IMPORTED TO DOMESTIC POTATOES. 

The total imports of potatoes into the United States make up a 
very small proportion of the total consumption, as may be computed 
from Table I. For the five years, 1907-1911, preceding the quaran- 
tine, the imports minus the exports were 1.03 per cent of the esti- 
mated production. 



16 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

Table I. — Acreage, production, value, prices, exports, a/id imports of potatoes in the 
United States, 1900 to 1912, inclusive. 



Year. 


Acreage 
planted and 
harvested. 


Average 

yield per 

acre. 


Production. 


Averag e 

farm 

price per 

bushel, 

Dec. 1. 


Farm value, 
Dec. 1. 


For fiscal vear beginning 
July 1. 


Domestic 
exports. 


Imports. 


1900 


2.611,000 
2,864,000 
2,966,000 
2,917,000 
3,016.000 
2,997.000 
3, 013, 000 
3,128,000 
3,257.000 
3,525.000 
3.720.000 
3.619,000 
3,711,000 


Bushels. 
80.8 
65.5 
96 
84.7 

110.4 
87 

102.2 
95.4 
85.7 

106.8 
93.8 
80.9 

113. 3 


Bushels. 

210,927,000 
187,598.000 
284, 633, 000 
247, 128, 000 
332,830,000 
260,741,000 
308,038,000 
298,262,000 
278,985,000 
376,537,000 
349.032,000 
292,737,000 
420,047.000 


Cents. 
43.1 
76.7 
47.1 
61.4 
45.3 
61.7 
51.1 
61.8 
70.6 
54.9 
55. 7 
79.9 
50.5 


890,811,000 
143,979,000 
134,111,000 
151, 638, 000 
150, 673, 000 
160,821,000 
157, 547, 000 
184, 184, 000 
197,039,000 
206,545,000 
194, 566, 000 
233,778,000 
212, 550, 000 


Bushels. 

741,483 

528, 484 

843. 075 

484, 042 

1,163,270 

1,000,326 

1,530,461 

1,203,894 

763, 651 

999,476 

2,383,887 

1,237,276 


Bushels. 
371,911 


1901 


7, 656, 162 
358, 505 


1902 


1903 


3, 166, 581 
181,199 


1904 


1905 


1,984,160 
176, 917 


1906 


1907 


403, 952 


190S 


8,383,906 


1909 


353,208 
210, 9S4 


1910 


1911 


13.734.095 


1912 






! 



THE 1913 POTATO CROP. 

The potato crop of the United States for 1913 is estimated to be 
238,946,000 bushels. The principal shortage is in the Central States, 
which are not the leading potato States. Comparisons to determine 
the actual needs of the country can not fairly be made with the 1912 
crop, which was so large that hundreds of thousands of bushels went 
to waste for lack of a market and millions of bushels were sold for 
less than the cost of production. 

The following is quoted from the department's Weekly News Letter 
to Crop Correspondents, January 28, 1914: 

Firmer Holding of Potatoes by the Farmers. 



SUPPLY IS NEARLY NORMAL, BUT DISTRIBUTION IS UNUSUALLY UNEVEN — PRINCIPAL 
rOTATO-PRODUCING STATES HOLD SUPPLIES, WITH SHORTAGE IN A NUMBER OF 
CONSUMING STATES. 

The yearly estimates of the amount of potatoes remaining in growers' hands and 
the stocks in dealers' hands on January 1 in the important potato States, just com- 
pleted by the Bureau of Statistics (Agricultural Forecasts), United States Depart- 
ment of Agriculture, indicate that a larger proportion of the marketable crop of 
potatoes was still in the hands of farmers on January 1 than had been the case for 
four years past. The proportion estimated to be in dealers' hands was smaller than 
for any year of the four except January 1, 1912. The figures showed that the total 
estimated potato production was below normal, but, owing to the slow movement of 
the crop up to January 1, the supply for the remainder of the year will be almost 
normal. Distribution, however, seems to be unusually uneven. The holdings of 
potatoes are relatively large in the important producing States of Maine, Michigan, 
Wisconsin, and Minnesota; and relatively small in New York, Ohio, Indiana, Illi- 
nois, Iowa, and Kansas, •which are important both as potato-producing and potato- 
consuming States. 

In consequence of the firm holding by farmers the price early in the season has 
been unusually high, being on December 1 about 17 J cents per bushel higher than 



THE POTATO QUARANTINE. 



17 



a year ago and 16 J cents higher than. three years ago, but 11 \ cents lower than two 
years ago, when potatoes on January 1 were selling for 77£ cents per bushel and the 
supply was unusually short, owing to the drought of the previous year. 

Present conditions do not seem to forecast material, if any, advance in prices in 
the important producing States this year. In 1911, when supplies were but mod- 
erately larger than now, and in 1913 the price movement after January 1 was down- 
ward instead of upward. The only other factor which may enter to change the 
experience of 1911 and 1913 is the somewhat different distribution of the crop which 
exists this year. 

Southern growers who plant in the spring for the early market would seem to be 
justified, from present conditions, in putting out a normal acreage, but should not 
expect the big advance in prices which prevailed two years ago. 

The estimates indicate that about 42.1 per cent of the marketable supply of pota- 
toes of the 1913 crop remained in the hands of farmers and 9.5 per cent in the hands 
of dealers on January 1 in the important potato-growing States. These figures com- 
pare with 39.8 and 9.8 per cent similarly estimated a year ago, 33.1 and 8.6 per cent 
two years ago, 40.2 and 10.9 per cent three years ago, and 41.2 and 9.9 per cent four 
years ago. If, for the purpose of comparison, these percentages were applied to the 
estimates of total production, it would show total stocks of 123,000,000 bushels on Jan- 
uary 1, 1914 (in the 19 States analyzed below), compared with 150,000,000 a year ago, 
91,000,000 two years ago, 133,000,000 three years ago, and 142,000,000 four years ago. 
These figures would indicate that the quantity to be carried toward the close of the 
season will not be sufficient to cause depressed prices, as was the case particularly 
four years ago (in some States last year, also), nor, on the other hand, will they be so 
scant as to cause such high prices as prevailed in the spring of 1912. 

To show the relation between supplies and prices, the following tabulation is 
given, showing for the past five years the production, stock on hand January 1, and 
the prices paid to producers on December 1 and the following March 1 in 19 impor- 
tant potato-growing States: 





Total pro- 
duction 
(bushels). 


Stocks on Jan. 1. 


Farm prices. 


Years. 


In growers' hands. 


In dealers' hands. 


Total 
(bushels). 


Dec. 1. 






Per 

cent 

of crop. 


Bushels. 


Per 

cent 

of crop. 


Bushels. 


Mar. 1. 


1913-14 


238,946,000 
304,126,000 
217,532,000 
261,141,000 
298,308,000 


42.1 
39.8 
33.1 
40.2 

41.2 


100,495,000 
119, 678, 000 
72,072,000 
104,954,0C0 
122 997,000 


9.5 
9.8 
8.6 
10.9 
9.9 


22,797,000 
30,167,000 
18,706,000 
28,463,000 
29,384,000 


123,292,000 
149,845,000 
90,778,000 
133,417,000 
142,381,000 


66.2 
48.6 
77.6 
49.5 
50.0 




1912-13 


47.7 


1911-12 


101.4 


1910-11 


46.9 


1909-10 


47.3 







A PROGRESSIVE POLICY NEEDED. 



The present situation emphasizes the fact that potato production 
in the United States is not on a sound economic basis. We have an 
almost regular alternation of seasons when more potatoes are pro- 
duced than can be consumed and prices fall below production costs 
in many instances and of seasons of short crops when prices are unrea- 
sonably high to the consumer. This condition is reflected in the 
imports and exports, as shown in figure 1. 



18 



BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 



It will be noted that during seven years of the twelve, more pota- 
toes wore exported than were imported, while during five years the 
imports exceeded the exports. 

The possibilities of potato production in the United States are 
almost unlimited. All of the States could increase their acreage and 
their average yield, and there exist in many northern districts, par- 
ticularly in Maine, Michigan, Wisconsin, and Minnesota, large areas 
of cut-over lands, recently in forest but now being brought under 
cultivation, which could produce many times more potatoes than at 
present. The same is true of the irrigated West. Under present 
economic conditions, however, no material increases in acreage could 
be made without risk of overproduction. 

Among the most striking features of potato culture in the United 
States are the low average yield per acre, the relatively high cost of 
production per bushel, the distance from markets of many important 



£?cpe/?rs 

3 S / 



3 *? 5 6 7 <P 3 



/O // /£ /3 /<? 




Fig. 1.— Exports and imports of potatoes for the United States during the years 1900 to 1911, inclu- 
sive, showing graphically the alternating seasons of overproduction and scarcity. 

potato districts, and the fluctuations in the market price, which make 
potato growing rather a speculative enterprise. 

To insure permanent prosperity there is a real need for the adoption 
of a constructive policy that will strike at the roots of the present 
difficulties, a policy of which quarantines or the regulation of imports 
are only minor phases, for foreign potatoes must of necessity in the 
future play a still smaller r61e than now in supplying food to the 
people of the United States as our population increases and as the 
European crop will be more and more needed for home consumption. 

PROTECTION FROM DISEASE. 

In view of the already excessive losses from diseases and insects, 
it is apparent that it is of national importance to prevent the intro- 
duction of more pests of this nature from other countries, a pro- 
tection which is afforded through the plant quarantine act. 



THE POTATO QUARANTINE. 19 

The quarantine law is, however, not the best means of controlling 
diseases already existent within our borders, for it does not provide 
authority for quarantining a single farm or a limited district in one 
of the States except as to interstate shipments. It is, therefore, of 
the highest importance that each State enact legislation authorizing 
the proper State officials to search for suspected cases of new or 
dangerous diseases and empowering them in the event of their dis- 
covery within the State to destroy infected stock or material, to put 
under quarantine the areas involved, and to take other measures 
needed to prevent the spread of the trouble. In some States such 
laws exist for nursery stock, but they do not always cover potatoes. 
It is particularly in States doing a large business in seed potatoes that 
such legislation is needed. 

The fact that many diseases, like the black-leg, dry-rot, scab, and 
eelworm, are scattered far and wide on infected seed also makes 
necessary some community or State action to control these troubles 
at the source by stimulating the growing of seed potatoes as a special 
business and by establishing a system of inspection and certification 
that will provide a means by which distant purchasers can be guar- 
anteed the freedom from disease of potato seed stock purchased, as 
well as its varietal purity and vigor. 

At present, the consumer shares the loss from potato diseases, 
whether in the field, in storage, or en route to market. Much of the 
loss can be prevented by better spraying or better methods of grading, 
handling, and shipping, which have not yet been worked out and 
adopted on account of a lack of concerted action and community of 
interest on the part of buyers, shippers, jobbers, and retailers. 
These men can assist the grower in lowering the present excessive 
retail prices of potatoes. 

LACK OF AN OUTLET FOR SURPLUS POTATOES. 

Under present conditions the production of potatoes is limited by 
the requirements of the market for table stock. A few culls are 
made into starch and a few fed to stock, but there is no extensive 
use of potatoes for industrial purposes such as one finds in Europe. 1 

Furthermore, the production in the United States is greatly 
influenced by weather conditions, especially by the occasional periods 
of heat or drought to which we are more subject than Europe and to 
which the potato is more sensitive than some other crops. 

The result is that when we acid to these two factors the natural 
tendency of farmers to reduce their acreage after a year of low prices 
and to increase it after a year of high prices, wa have the excessive 
fluctuation in supply and market prices already described. 

!Cf. Department of Agriculture, Bulletin 47. 



20 BULLETIN 81, U. S. DEPARTMENT OF AGRICULTURE. 

Some means of disposing of surplus potatoes is an economic neces- 
sity. If this can be done at a price reasonably above the cost of 
production, the potato crop will increase and a reserve supply of 
potatoes grown for industrial uses will be established that will meet 
the needs of all short years. 

Diversification or the introduction of better farming systems will 
be a step in this direction. Means should be worked out for keeping 
more live stock, especially swine, on potato farms, and a better 
understanding of the feeding value of potatoes and of the best 
rations combining potatoes with other feeds should be secured. 

The industrial uses of potatoes for starch, dextrin, alcohol, etc., 
require investigation in the United States. Perhaps the most press- 
ing need along this line is the adaptation of a method of drying j)ota- 
toes, as practiced in Germany, to American conditions, to the end 
that surplus quantities and culls of this perishable product may be 
preserved and by removal of its water rendered transportable to 
market. This problem is closely connected with that of varieties, 
for the starch content of most American potatoes is low, often too 
low for profitable drying. Breeding for higher starch content needs 
to be promoted, as well as breeding for table qualit}^ productivity, 
and disease resistance. 

A nation-wide cooperation for the solution of these different phases 
of the potato question should not leave out of consideration the 
problem of values from a national viewpoint: That the cost of pro- 
ducing and distributing potatoes should be kept down to such a point 
that the market price of this staple food shall be comparable with 
other staples. Marketing investigations and related problems of 
distribution demand active supjDort. 

o 





BULLETIN OF THE 

MPMrlTOFAfflLI 

No. 82 

Contribution from the Bureau of Plant Industry, Wm. A, Taylor, Chief, 
April 6, 1914. 

(PROFESSIONAL PAPER.) 

POVfDERY SCAB (SPONGOSPORA SUBTERRANEA) 

OF POTATOES. 1 

By I. E. Melhus, 
Pathologist, Cotton and Truck Disease and Sugar-Plant Investigations. 

INTRODUCTION. 

The comparatively recent discovery of Spongospora subterranea in 
the United States makes it necessary to introduce to the potato 
grower, importer, and pathologist a new potato disease. This disease 
is commonly known as powdery scab, and mild attacks of it resemble 
superficially the common Oospora scab. Its prevalence in many 
European countries and the Dominion of Canada has prompted the 
Secretary of Agriculture to extend, for a. time at least, the present 
quarantine on foreign potatoes. 

Although powdery scab has probably been known to exist in 
Europe since 1841, it was not until within the last decade that it 
assumed an important role in pathological literature. It has been 
most extensively studied by pathologists in the British Isles, where 
powdery scab is said to be very common. 

In February, 1913, Spongospora was reported for the first time in 
North America. It was collected in several provinces of Canada by 
the Dominion Botanist, Dr. H. T. Gtissow (1913), 2 who has expressed 
the opinion that the first introduction into Canada must have been at 
least seven years previous. Dr. W. J. Morse (1913), of the Maine 
Agricultural Experiment Station, and the writer (1913) obtained 
evidence daring the summer of 1913 showing that this disease exists 
in the United States. It seems probable that it was introduced with 
the heavy shipments of foreign potatoes in 1911 before the quarantine 
law against the wart disease went into effect, Sufficient evidence 
is at hand to show that powdery scab will make inroads on the 
potato industry unless proper precautions are taken, and it is the 

1 This paper will be of interest to plant pathologists and to potato growers in the northern and southern 
potato-growing sections. 

2 The dates in parentheses refer to the bibliography printed at tfhe end of this bulletin. 

30951°— 14 



2 BULLETIX 82, U. S. DEPARTMENT OF AGBICULTTJEE. 

object of this bulletin to call attention to this fact an<3 ask the con- 
d effort of all interested in the potato industiy to prevent the 
spread of this malady. 

COMMON NAME OF THE DISEASE CAUSED BY SPONGOSPORA. 

Spongospora, like many other fungi, has been given a variety of 
common names. In Germany it was early known as "Kartoffel- 
raude " (Wallroth, 18426) among the farmers. By Wallroth (1842a), 
who first recorded its occurrence and who considered it a smut, it 
was given the common name "Knollenbrand." According to 
Brunchorst it is called " Skorv" in Norway, and is identical with the 
disease known as "Schorf" or " Grind" in Germany. In the British 
Isles, where it has been most intensively studied, it has been called 
corky end, corky scab (Johnson, 1908), powdery scab, Spongospora 
scab, and potato canker. The name powdery scab, which was first 
applied to it by Johnson, of Ireland, is in most common use at the 
present time. This name has reference to a characteristic symptom 
of the mature spot, or sorus, as it appears when the infected tuber 
is dug from the ground. 

SCD2NTD7IC NAME OF POWDERY SCAB. 

The scientific name of Spongospora has been changed even more 
often than its common name. This has probably been due (1) to the 
imperfect understanding of the life history of the fungus and (2) to 
the superficial resemblance of the spore balls of Spongospora to those 
of the smuts. Wallroth (1842&), who first collected Spongospora in 
1841, named it Erysibe subterranea. It was described and figured by 
Martins (1842) as Protomyces tuberum solani. In 1844 Rabenhorst 
concluded it was not a species of Erysibe and described it in a new 
genus, Rliyzosporium solani. That Berkeley (1846) was familiar with 
the fungus and knew that it had been reported previously is apparent 
from a short note in one of his articles on the potato murrain published 
in 1846. He mentions Martius's Protomyces and figures the spore 
-. choosing, however, to call it Tuburcinia scabies (Berkeley, 1850). 
The name of the organism was again changed in 1877 by Fischer von 
Wuhlheira, who placed it in another genus and called it Sorosporium 
scabies Berk. 

It was not until 1886, when Brunchorst found Spongospora on 
potatoes in Norway, that it was shifted into the correct group, namely 
the Myxomycetes. Why Brunchorst failed to recognize or mention 
any of the earlier descriptions of Spongospora is not explained in his 
paper. That he was aware of the fact that the same disease existed 
in Germany and perhaps in England is evident from the following 
sentence : 

Was. das Vorkommen dcs Spongospora betrifft, ist derselbe bier in Norwegen 
aus=erst verbreitet; wenn es 6ich. bestatigen sollte, was ich sicher glaube, dass dec 



POWDERY SCAB OF POTATOES. 3 

Pilz die Ursache der in Deutscliland "Schorr" genannten Krankheit ist, und viel- 
leiclit audi der "Scab" der Englander, wiirde auch sonst die Verbreitung eine ganz 
ansehnliche sein. 

Nevertheless he described it anew as Spongospora solani, and this 
name was in general use until 1908, when Massee (1908 and 1910) 
described it as Spongospora scabies, combining Brunchorst's generic 
name and Berkeley's specific name, a combination which is re- 
ferred to by Pethyb ridge (1913a) as not necessary and untenable. 
Johnson, of Ireland, used the name applied by Brunchorst until 
1909, when he found evidence to show that Brunchorst's Spongospora 
solani was identical with Wallroth's Erysibe subterranea. In an 
article published in 1911, Home is unable to confirm Johnson and 
questions whether the organism described and figured by Wall- 
roth, Martius, and Berkeley really is the same fungus described by 
Brunchorst. In view of this fact he adheres to Brunchorst's Spon- 
gospora solani. 

In a very recent article Pethybridge (1913a) brings forth still more 
evidence to establish the identity of Wallroth's Erysibe subterranea 
and the organism now known as Spongospora. He also emphasizes 
the fact "that the question of identity does not rest merely upon the 
degree of accuracy with which the spore balls are figured, but some 
regard must also be paid to the very full description given by Wall- 
roth of the development and fate of the warts, which agrees fully 
with what we know of the behavior of Spongospora and which does 
not apply to any other organism known at present." Judging from 
the evidence now available as to the specific name of Spongospora, 
it seems clear to the writer that it should be that first used by John- 
son, namely, Spongospora subterranea (Wallr.) Johnson. 

DESCRIPTION OF THE DISEASE. 

This disease, so far as is known, never attacks the aboveground 
portions of the potato plant. It is primarily a disease of the young 
tubers, which develops as they mature in the ground. The earliest 
stages of infection, according to Osborn (1911), "are visible on young 
tubers not larger than hazelnuts. The disease is apparent by small 
slightly raised pimples and a slight discoloration of the surface. 
When cut open, the infected areas appear faintly purplish and 
extend from approximately the outermost cells of the tuber toward 
the deeper layers. Actual infection of the potato tuber by Spongo- 
spora has not been seen, nor have infection experiments been success- 
ful. The earliest stage in the fife history that has been observed is 
that of a single uninucleate amoeba in a young potato cell near the 
eye." Once in the tissues these naked masses of cytoplasm consume 
the cell content and multiply rapidly, as shown in Plate I, A, and at 
the same time stimulate the host cells to further growth and division. 



4 BULLETIN 82, U. S. DEPARTMENT OF AGRICULTURE. 

It seems established that the amoebae pass from one cell to another 
when cell division takes place, although it is claimed by Massee (1908) 
that the amoebae invade new cells by boring through the cell walls. 
On the other hand, Osborn (1911), who has made an extensive cytolog- 
ical study of this organism, holds that "on the division of the host 
cell * * * it is a purely fortuitous circumstance whether each 
resulting cell shall contain an amceba, and so be infected or not. 
* * * I have never seen any signs of the migration of an amoeba 
to a neighboring cell nor any continuity of protoplasm, such as 
Massee has described." Osborn' s contention as to the method of 
migration of the amoebae has been confirmed by Home (1911). The 
abnormal local increase of cells causes a swelling and a faint discolor- 
ation of the skin, which latter becomes a wartlike outgrowth. The 
fungus present in this tissue consumes largely the contents of the 
ceHs (PI. I, C, D), after which the amoebae coalesce (PI. I, C, D) and 
form one or more large spongy masses in each cell, known as plasmodia 
(PI. I, D). These latter divide into many small spores, each of which 
takes on a heavy yellowish brown wall (PI. I, E). Instead of these 
spores separating, they remain attached, forming a "spongelike body," 
according to Johnson (1908), and not a hollow sphere, as reported by 
Berkeley (1846) and Massee (1910). 

Since the contents of the attacked host cells are used up in form- 
ing spore balls, the infected area becomes a pit filled with a yellow- 
ish brown dust consisting chiefly of spore balls (PI. II, C). These 
pits, or son, at maturity are bordered by the torn skin of the tuber. 
The torn skin standing up on the periphery of the sorus is one of the 
characteristics of powdery scab, which often enables one to dis- 
tinguish it from the Oospora scab macroscopically. The powdery con- 
tents of the sori in this stage of the disease doubtless suggested to 
Johnson the name "powdery scab," as has already been noted. It 
has been observed that in storage shriveling and shrinkage take place 
about these pits, or sori. How generally this shriveling occurs and its 
significance are not known up to the present writing, nor have these 
matters been emphasized in the literature, to the writer's knowledge. 
The cause of this shrinkage is not known, but it may possibly be due 
to insufficient cork deposition in the bottom of the sori which afford 
an avenue for storage rots to attack the infected tuber. 

When conditions are highly favorable for the fungus, it may eat 
large cavities in the immature tubers. Besides consuming part of 
the tubers, it stunts their further growth and produces malformed 
tubers, such as are shown in Plate III. The nature and extent of the 
depressions caused are shown in Plate III, C. This stage of the dis- 
has been called the cankerous stage (Home, 1911) and is the 
one that causes the greatest loss. 



Bui. 82, U. S. Dept. of Agriculture. 



Plate I. 




P 




S&, 



\<m 






{#•.■ 













E 










Various Stages in the Life History of the Fungus which Causes 
Powdery Scab. 

A, A large host cell in which there are three amcebse of Spongospora. B, A young host 
cell in the early stages of infection. The amoeba lies just below the nucleus. C, The 
amcebEe are coalescing to form the Plasmodium. U, The plasmodial stage. E, Mature 
spore balls in an enlarged host cell. (A to E, after Osborn.) F, The isolated spore 
balls photographed. Note the variation. (Original.) 



Bui. 82, U. S. Dept. of Agriculture. 



PLATE II. 




Four Tubers (A, B, 0, and 1>) Infected with Spongospora Subterranea Col- 
lected in New Brunswick, Dominion of Canada, on October 1, 1913. 

They represent the scabby stage of the disease. The sori niiiy be either isolated or grouped, 
us shown in .1 and B. The variation in size and general appearance of the sori is 
brought out in Cand I>. In the tuber marked 1) the sori are only about half as large 
and more superficial than in C. Two tubers infected with Oospora scab are shown as 
E and F. 



Bui. 82, U. S. Dept of Agriculture. 



Plate III. 




The Cankerous Stage of Sponqospora. 

It is this stage that is most destructive to the potato tuber. The cavities and large pustules 
combine to cause malformation of the tubers. In C is shown a section through a tuber 
badly infected with Spongospora. (A, B, D, and E are after Home. C after Gussow.) 



POWDERY SCAB OF POTATOES. 5 

GEOGRAPHICAL DISTRIBUTION OF POWDERY SCAB. 

Spongospora seems to be quite generally distributed in northern 
Europe. As early as 1841 it was recorded as existing in Germany, 
and that it had existed for some time before this is suggested by the 
fact that among farmers the disease had come to be known by a com- 
mon name (Kartoffelraude). Frank more recently (1897) has men- 
tioned its existence in Germany, but he does not think it is generally 
distributed. That it does exist to some extent, and possibly more 
than Frank's report indicates, is suggested by the following facts: 

In the spring of 1913 the Bureau of Plant Industry purchased 22 
different varieties of seed potatoes from two dealers in Germany. 
When these were received and examined by the inspecting patholo- 
gist, four of the lots were condemned, being infected with Spongo- 
spora. 

In 1846 powdery scab was discovered in England by Berkeley in 
connection with his studies of the potato murrain, the disease which 
is now known as PTiytoplithora infestans. The little careful study that 
was given to Spongospora by the pathologists of Berkeley's day may 
well have been due to the intensive study given to the Phytophthora 
disease, which at that time threatened to destroy the potato industry 
of northern Europe. The general distribution of Spongospora in 
England and Scotland at the present time can readily be seen from 
the following statement of the Board of Insect and Fungous Pests 
for 1909: 

It has been reported to the board from many parts of Great Britain, chiefly, how- 
ever, from those parts where wart disease is also present, or where it has been sus- 
pected. Cases have been reported from Peebles, Stornoway, Forfar, Fife, Lanark, 
Aberdeenshire, Sthlingshire, Lancashire, Cumberland, Shropshire, Rorks, W. W., 
Staffordshire, Wales, Hereford, Somerset, and Worcester. In Scotland, therefore, the 
disease seems fairly widely distributed, but in England, as might be expected, it 
appears to be confined to the west, where the rainfall is higher. It is not, however, 
to be supposed for a moment that anything like all affected localities are here recorded. 

In the spring of the current year the United States Department of 
Agriculture imported 18 different varieties of potatoes from Scotland 
for seed purposes, all of which were found to be infected with Spongo- 
spora and were condemned by the inspecting pathologist. Nine dif- 
ferent varieties were imported from England for similar purposes and 
were not allowed to pass, owing to Spongospora infection. 

On October 31, 1913, Mr. W. W. Gilbert, of the Bureau of Plant 
Industry, collected specimens of powdery scab on potatoes imported 
into this country from the Netherlands. On November 20 the writer 
likewise collected Spongospora at New York City on two different 
shipments from the Netherlands. The following day specimens were 
taken by Mr. O. A. Pratt and the writer from a shipment coming from 
Belgium. More recently the disease has been found several times 



6 BULLETIN 82, U. S. DEPARTMENT OF AGRICULTURE. 

in considerable quantity on potatoes coming from the Netherlands 
and Belgium. As already stated, the disease has been in Norway 
since 1SS6 and has since been found in Sweden. 

It is also interesting in this connection to note that Spongospora 
occurs in South America, probably the native habitat of the potato. 
It was collected in 1891 at Quito, Ecuador, by Lagorheim, who reports 
that the disease is well known to the natives. This suggests two 
possibilities : (1 ) That the disease has always existed there or (2) that 
It was introduced into South America on European varieties. 

PRESENCE OF POWDERY SCAB IN CANADA. 

More recently powdery scab has gained a foothold in North 
America, and early in the spring of 1913 it was reported in several 
Provinces of Canada by Giissow. The writer has been able to confirm 
Giissow's reports by personally visiting the potato-growing sections 
in three of the Provinces of Canada, namely, New Brunswick, Prince 
Edward Island, and Nova Scotia. It was found that powdery scab 
was quite generally distributed in the lower St. John River valley, 
New Brunswick, and on Prince Edward Island. 

POWDERY SCAB IN THE UNITED STATES. 

That Spongospora exists also in the United States has been defi- 
nitely established. In the spring of 1913 Morse, of the Maine Agri- 
cultural Experiment Station, obtained some evidence that the disease 
exists in Nebraska and Massachusetts. No further cases have been 
reported from these States. In June, 1913, the writer collected 84 
tubers infected with Spongospora from four barrels of the Green 
Mountain variet}" purchased for experimental purposes at Presque 
Isle, Me. These had been grown in the vicinity of the village during 
the season of 1912. 

Spongospora was collected at Washburn, Me., on February 9, 
1914, and at Frenchville on the following day. Later it was found 
at stations farther south in Aroostook County. 

A thorough survey of northern Maine is now being made by the 
State department of agriculture, with the cooperation of this depart- 
ment. The survey to date indicates that powdery scab is more 
common in the northern half of Aroostook County. Several cases 
were found where the growers at some time during the last three or 
four years had secured seed from the neighboring infested sections 
of New Brunswick, which may well account for the introduction of 
the disease. The results secured up to the time this bulletin goes to 
press indicate that there is considerable powdery-scab infection in 
Aroostook County. The active measures that are now being taken 
to discover and delimit the infected areas and to prevent the ship- 
ment of diseased potatoes for seed purposes should result in checking 
the spread of powdery scab. 



POWDERY SCAB OF POTATOES. 7 

DAMAGE TO THE POTATO CROP. 

The scabby stage of Spongospora, like the common Oospora scab, 
is a skin disease confined to the tubers, marring their appearance 
and thereby decreasing their market value. The cankerous stage, as 
shown, in Plate III, completely destroys the tubers for both food and 
seed purposes. This observation is confirmed by the following 
quotation from Pethybridge (1911, p. 442); 

As was pointed out last year, Spongospora scab presents two forms of attack, In the 
one case that of small spots on the surface of the tubers, and in the other the form of 
a " canker " or eating away of the tuber. This latter is, of course, the most serious one, 
but there are all degrees of transition between it and the spot form. 

Pethybridge is inclined to classify the effect on the potato as 
producing "scab spots" and "cankers," the former doing little harm 
to the tuber, while the latter, as shown by his illustrations, com- 
pletely deform and dwarf its growth, so as to make the tubers 
worthless. 

Osborn (1911) holds that the soil moisture determines to a great 
extent the damage done by the disease and says — 

Under dry conditions of the soil the external appearance is limited to small circular 
patches about 5 mm. across. Under wet conditions the damage is more serious and 
the scabs may be as large as 3-4 cm. in diameter and as much as 2 cm. in depth. This 
is the only external appearance; there is no sign of hypertrophy or any distortion other 
than that caused by the pitting. 

The presence of the fungus in the cells stimulates the host to lay 
down a new layer of cork cells surrounding the sorus, if the soil is 
not too wet, which checks its growth. 

By Giissow (1913), who has, as already stated, found powdery 
scab in Canada, the disease is not considered trifling. He says — 

The disease should by no means be regarded lightly. Severe attacks occur when 
potatoes are planted year after year on infected land. Where this is practiced the 
result will be potatoes hardly superior in quality to those badly affected with canker. 
This fact is worthy of notice, especially since, as In the case of canker, no preventive 
measures have proved of much value. 

In a very recent publication, Pethybridge (19135, p. 459) refers to 
the damage done by Spongospora in his experimental plats, as 
follows : 

They were particularly disastrous on those . portions of the land which for special 
purposes have now been cropped for four successive seasons with potatoes, the cankerous 
form of the disease being extremely common. In one or two plats nearly two-thirds 
of the total crop were practically ruined by it, while the general average loss in the 
plats on the old land due to it would be about one-third of the crop. 

EFFECT ON SEED POTATOES. 

Besides injuring the potato for market purposes and decreasing 
the yield, as already, noted, powdery scab also depreciates the value 



8 BULLETIN 82, U. S. DEPARTMENT OF AGRICULTURE. 

of the potato for seed purposes. Its harmful effect on the seed has 
boon emphasized by Johnson (1908, p. 453), as follows: 

Such tubers are not only much reduced in market value for eating purposes, but 
must provide also poor seed for the next year's crop. Yet I was constantly told that 
this was the kind of seed regularly planted from year to year; and that the people 
used this seed because they had, and could get, no other. * - * I have no doubt 
myself that this Spongospora scab has a good deal to do with the miserable average 
yield per acre of potatoes in the west of Ireland. * * * It is in some districts of 
Ireland as injurious to potatoes as finger -and-toe is to turnips. 

The following sentence from Pethybridge's report in 1911 (p. 442) 
shows more strikingly the relation of the disease to the seed potato: 

It was found during the past season that the crop resulting from the planting of the 
"canker" form of disease in clean land gave 67.1 per cent of affected tubers, while 
the spot form produced only 54.1 per cent. 

That other countries are not considering Spongospora scab lightly 
is apparent from a farmers' bulletin, No. 110, of the Transvaal 
Department of Agriculture, issued by Evans in 1910, warning the 
grower against the use of infected seed potatoes. Evans says- — 

Corky scab has caused a considerable amount of damage to the potato crop in Great 
Britain, Ireland, and Norway. It also occurs in Germany, and is particularly preva- 
lent in the west of Ireland. * * * Diseased tubers should on no account be used 
for seed purposes, for not only will the resulting crop be scabbed, but the ground will 
also be infected with the germs of the parasites. 

It must also be remembered that not only does powdery scab 
injure the crop, but the soil becomes contaminated and clean seed 
planted on this land for several years afterwards becomes infested. 
Just how long the organism can remain alive in the soil is not known, 
but that it is resistant and may live for several years is suggested 
by the structure of the spores and experiments by Pethybridge (1911) 
showing that the spore balls can pass through an animal without 
losing their capacity for renewing the disease. Contamination of 
clean seed may take place, it is claimed, by simply being in contact 
with diseased potatoes. If such is the case, and there is good reason 
to believe it possible, clean seed may become infected through the 
use of old bags and machinery. Indeed, it is even possible for one 
field to become infested from another by the spore balls being carried 
by the wind, water, and other agencies. 

IS POWDERY SCAB A DANGEROUS MALADY? 

In considering whether powdery scab is or is not a dangerous 
disease it is well to keep in mind that any inciting agent, regardless 
of its origin or nature, that mars or defaces the tuber depreciates its 
value and ultimately its productiveness. The degree of danger pre- 
sented by this intruder is problematical, but all American plant 
pathologists who have expressed an opinion upon this point are 
agreed that powdery scab is a disease possessing characteristics that 



POWDERY SCAB OF POTATOES. 9 

might make it a serious enemy of the potato in the United States, at 
least as bad as the common scab caused by Oospora scabies, and prob- 
ably worse. 

The effect of the milder form of Spongospora upon the tuber resem- 
bles that of the common scab in that it disfigures the potato and 
thereby reduces the market price, even though the food value may 
not be materially impaired. It differs from Oospora scab in that the 
advanced or cankerous stage ruins the tuber for both table and seed 
purposes. 

In this connection it should be remembered that any kind of scab 
or other injury that mars or defaces the potato tuber is a more serious 
handicap in the American markets than in those of some European 
countries, due to the fact that consumers abroad offer fewer objec- 
tions to scabby potatoes than consumers in the United States. There 
is even a belief prevalent abroad that scabbiness is an indication of 
superior quality. In the United States, when potatoes are put on 
the market, scabby potatoes must be sorted out, and therefore are 
of no use except for stock feed or the manufacture of starch. In 
Maine the price of scabby potatoes in the autumn of 1913 was 50 
cents per barrel, while clean stock brought $1.50 per barrel. In the 
country as a whole, hundreds of thousands of bushels of potatoes are 
left in the fields because they are too scabby to market. There are 
frequent instances in the New York markets, according to potato 
dealers, where carload consignments are rejected because of the 
presence of numerous scabby potatoes. When the soil becomes in- 
fested with scab its value as potato land materially depreciates. This 
is especially true in sections where potatoes constitute the chief crop. 

The character and relationship of the parasite should also be 
taken into consideration in judging the danger which powdery scab 
presents. This is a ^ase of dealing with a slinie mold, a relative of 
the serious disease of cabbage, turnips, and related plants, known as 
clubroot. 

If powdery scab should prove no more troublesome in the United 
States than it has been up to the present in Europe, it would be rated 
as a disease of secondary importance as compared with late-blight or 
with Fusarium wilt. But there are reasons for fearing that it may 
become more prevalent here. It seems to be a fact that common scab 
is less troublesome in Europe than in America, and the same condition 
might be the case with powdery scab. It quite often occurs that 
introduced parasites are more destructive in a new habitat than in 
their native environment. Likewise, it is not impossible that Spon- 
gospora may find the American varieties of potatoes more sus- 
ceptible than the European sorts. There is also no means of pre- 
dicting the behavior of Spongospora under the varied climatic and 
soil conditions of the several States. The parasite has only recently 



10 BULLETIN 82, U. S. DEPARTMENT OF AGRICULTURE. 

been found on the American Continent, and the brief experience with 
it in eastern Canada gives no hint of what its behavior would be in 
the southern trucking districts, the central West, or the irrigated 
sections. The common scab is much worse in many parts of the West 
than in the East. 

Another reason for grave concern in the United States is that the 
disease exisis in that portion of Canada adjoining the State of Maine, 
which is the chief source of seed potatoes for the Central Atlantic and 
Southern States. If powdery scab becomes generally distributed in 
Maine, only the most extraordinary efforts can check its spread to 
nearly every State in the Union. 

MACROSCOPIC DIFFERENCES BETWEEN SPONGOSPORA AND OOSPORA 

SCAB. 

It should be made clear in discussing the similarity of and differ- 
ences between Spongospora and Oospora scab that the symptoms and 
ultimate effect on the tuber vary markedly in the case of both dis- 
eases, depending upon external influences. In spite of the wide 
variation of powdery scab, two characteristic stages of the disease 
may be recognized, namely, the scabby and the cankerous stages, 
shown in Plates II and III, respectively. It is only the former of 
these that can be easily confused with the Oospora scab, and there- 
fore the latter stage needs no further consideration in this connection. 

As pointed out by Home, the early stages of Spongospora resemble 
markedly the beginning stages of the wart disease caused by Chryso- 
pldyctis endobiotica, in that wartlike excrescences appear on the 
tuber. Such symptoms are in no way like those of the early stages 
of Oospora scab, and this naturally leaves for comparison only the 
characteristics of the two diseases as found on the mature tuber at 
harvest time and shortly thereafter. 

The scabby stage of Spongospora on the mature tuber, as illus- 
trated in Plate II, usually differs essentially from Oospora scab in 
three ways : 

(1) The sori are more often circular and not usually as great in 
diameter as those of Oospora scab. 

(2) The periphery of each sorus is bordered by the upraised outer 
epidermal layer of the tuber, so that virtually small cups or pits are 
formed, as shown in Plate II, B and C. 

(3) These pits are usually deeper than those of common scab and 
are always filled at maturity with a brownish colored semicompacted 
dust or sediment, as shown in Plate II, C. The sori of Oospora are 
usually shallow and composed of corky material of a compact and 
interwoven nature. 

It should be remembered that it is extremely difficult, if not 
impossible, to define the difference between two diseases varying so 



POWDERY SCAB OF POTATOES. 11 

markedly under diverse environmental conditions. In fact, many 
cases have come to the attention of the writer where the macroscopic 
characteristics mentioned were not in evidence, and yet the typical 
spore balls were found in the sorus upon making microscopic exami- 
nation. It should be especially emphasized that the three differen- 
tial characteristics pointed out may be totally absent after the 
infected tuber has been harvested and roughly handled through ship- 
ment. 

In Plate II are illustrated what may be called common cases of 
Spongospora and Oospora scab. The upper four potatoes are 
infected with powdery scab and the lower two with common, or 
Oospora, scab. 

FUNCTION OF THE SPORE BALLS AND METHODS OF INFECTION. 

The potato crop probably becomes infected by the spore balls 
present in the soil or on the sets when planted. Just how infection 
takes place is not known. Infection studies are made difficult 
because no one has been able to germinate the spore balls in abundance 
at will. Massee (1908) claims that the content of each spore is 
liberated as a whole in the form of irregularly globose bodies with a 
few small projections. These bodies show a slow, sluggish move- 
ment for some time and then come to rest. Each amoeboid body is 
about 3 /t in diameter and uninucleate. Johnson (1908) saw motile 
bodies resembling swarm spores in his cultures which he believed 
were the swarm spores of Spongospora, but he states that he never 
saw them escape from the spore. Instead of being uninucleate, he 
found them to have from one to eight nuclei, like the swarm spores 
of Ceratiomyx. Both Osborn (1911) and Home (1911) have 
attempted to germinate the spore balls without being able to confirm 
either Massee or Johnson. It may be that their germination is sea- 
sonal, like the spores of a goodly number of other fungi, or that some 
special stimulus in the soil is necessary to cause them to become 
active. That they function can not be doubted, because clean seed 
planted in soil infested with Spongospora spore balls becomes infected 
with the disease, as shown by Home's experiments. 

It has also been proposed by Massee (1910) that the plasmodia may 
become encysted during the winter and resume their activity when 
the tubers begin to sprout, and Johnson (1909) holds that the Plas- 
modium may migrate from the diseased parent tuber into the stem 
and stolons of the young plant and ultimately infect the young tubers. 
As suggested by Home, neither of these investigators has proved 
experimentally that the plasmodium ever assumes such a r61e. It 
can not help but become obvious that more information as to the 
method of functioning of the spore balls and the method of infesting 



12 



BULLETIN 82, IT. S. DEPARTMENT OF AGRICULTURE. 



the soil under field conditions is much needed in order to understand 
clearly this disease. Such studies are also necessary before control 
measures can be intelligently worked out. 

SEED TREATMENT. 

Powdery scab has received little attention from the standpoint of 
control measures except in Ireland, and the results obtained are not 
fully convincing. Johnson (1908) states that soaking infected tubers 
18 to 24 hours in 2 per cent Bordeaux mixture, or 1 per cent corrosive 
sublimate for 1| hours, or 4 per cent formaldehyde solution for 2 
hours, is effective in killing the spore balls. It has already been 
emphasized that very little is known regarding the germination of 
the spores. 

Pethybridge (1911, p. 443) has also studied to some extent the 
control of Spongospora. His results are shown in Table I. 

Table I. — Yield of diseased potatoes when seed was untreated and following various 

treatments for powdery scab. 



Xo. of 
plat. 



Treatment of seed potatoes, if any. 



Yield of 
diseased 
tubers. 



Xo treatment; seed only slightly affected 

Xo treatment; seed badly affected 

Soaked in formalin solution (1: 600) for 3 hours 

Soaked in copper-sulphate solution (1 per cent) for 3 hours 

Soaked in copper-sulphate solution followed by rolling in slaked lime 

Soaked in and covered -with precipitate of Burgundy mixture for 3 hours 
Surface 'wetted and rolled in flowers of sulphur 



Per cent. 

54.1 

67.1 

2.6 



4.4 
2.9 
1.03 



Regarding these experiments, Pethybridge says — 

From the table it ■will be seen that in all cases the treatment of the seed, tubers 
resulted in a most satisfactory checking of the disease. With regard to plats 8, 9, 
and 10, where copper salts were used, the total yield of tubers was, however, quite 
considerably reduced. The best yield was given with the formalin treatment, and 
the next best with sulphur. Of these two, perhaps, the sulphur treatment would be 
the easier to put in practice. 

The results obtained by Johnson and Pethybridge are very inter- 
esting, but are of a preliminary nature, requiring further study before 
they can be recommended for practice. 

SOIL TREATMENT. 

Soil treatment with fungicides for Spongospora scab, as would 
naturally be expected, has given experimenters but little encourage- 
ment. This matter has been most extensively studied for the past 
three years in Ireland by Pethybridge (19136, p. 460), whose most 
recent results follow. 



POWDERY SCAB OF POTATOES. 



13 



Table II. — Yield of diseased potatoes when soil was untreated and following various 

treatments for powdery scab . 



No. of 
plat. 



Treatment of land, if any. 



Total 
yield 
per 
square 
perch. 



Yield 
of dis- 
eased 
tubers. 



Extra superphosphate added, 4 hundredweight to statute acre. . . 

Each tuber planted in a handful of wet sawdust 

Extra sulphate of potash added, 1 hundredweight to statute acre 

No treatment 

do 

Extra muriate of potash added, 1 hundredweight to statute acre. 
Flowers of sulphur applied, 65- hundredweight to statute acre 



Pounds. 

99 

74 

102.5 
100 

97 

94 

ioe 



Per cent. 
30.3 
34 
38 
51 

52.5 
52.1 
23.6 



Pethybridge writes as follows regarding these experiments: 

With the exception of the muriate of potash, it will be seen that considerable diminu- 
tion in the weight of diseased tubers produced has been effected by the methods of 
treatment used, although the use of sawdust has reduced the total yield. The yields 
given in the above table are pounds per square perch. 

The best results were obtained with sulphur, where not only was the amount of 
disease reduced to less than one-half of that in the untreated plats, but the total yield 
was higher than in any other case. This result confirms previous experiments carried 
out at Clifden, which have always shown that sulphur added to the soil increases the 
yield of potatoes and diminishes the attack of scab. * * * 

Substantial as are the reductions in the amount of scab due to the methods of soil 
treatment above indicated, they cannot be looked upon from the practical standpoint 
as sufficient, and a suitable, cheap soil disinfectant is still a great desideratum for this, 
as well as for other purposes. 

liming the soil, as is practiced for clubroot of cabbage, a parasite 
related to Spongospora, has proved an aid to the fungus rather than a 
check to its development. This makes it clear that it does not 
behave like clubroot of cabbage, as suggested by Massee. The effect 
of lime on the development of Spongospora has been pointed out by 
Home (1911) and Pethybridge (1911). 

It is, of course, obvious, as Pethybridge suggests, that there is as 
yet no method of controlling this disease when it once gets into the 
soil. In view of this fact, it is plain that potatoes should not be 
grown for some years on a piece of land that has produced a crop 
infected with Spongospora scab. Just how many years the fungus is 
able to remain alive in the soil is not known and is a question that 
merits investigation. The nature of the spore balls suggests that the 
disease may well be able to live in the soil for several years. It 
should be said also in this connection that if more was known as to the 
germination of the spore balls, it might be possible to predict their 
longevity. 



14 BULLETIN 82, U. S. DEPAETMENT OF AGEICULTTJBE. 

SACKS AND BARRELS AS AGENTS IN SPREADING POWDERY SCAB. 

It is well known that secondhand sacks, barrels, and boxes are 
often used in marketing potatoes. 

Seed potatoes shipped from the Northern States to be grown in the 
South are put up either in sacks or barrels. European potatoes com- 
ing to this country are shipped in 168-pound gunny sacks. In some 
of the Western States similar sacks, but holding only 120 to 150 
pounds, are used. These sacks cost from 12 to 16 cents each, depend- 
ing upon their quality and whether they are new or secondhand. 
Sacks of good quality can be used many times, and this has come to be 
common practice. In both New York and Boston there are firms 
that act as clearing houses for jDotato sacks, buying secondhand sacks 
from anyone who may wish to sell them and shipping them to potato 
dealers either north or south. It may happen, therefore, that sacks 
that have previously contained diseased tubers coming from Europe 
or elsewhere will be used for shipping select seed from the North to 
the South. It is not improbable, and, indeed, very possible, that 
spores of Spongospora, Spondylocladium, Fusarium, Phytophthora, 
etc., may be communicated to healthy potatoes through secondhand 
sacks. The same thing may take place through using secondhand 
barrels, but this is not so often done. There is, however, considerable 
chance of potato diseases being spread by means of old sacks. 

The question arises as to how this spreading of disease can be pre- 
vented and, of course, the solution is a simple one — by using only 
new sacks. But this would increase to some extent the cost of pota- 
toes and bring about the accumulation of large quantities of old sacks. 
It seems very likely that some means of sterilizing old sacks could be 
put into practice which would make them fully as harmless as agents 
in disseminating diseases as new sacks. This could probably best be 
carried out by firms dealing in sacks. It seems probable that sub- 
jecting the sacks to steam sterilization for several hours at a pressure 
of 15 to 20 pounds would render them free from noxious diseases with- 
out increasing their cost to any appreciable extent. 



BIBLIOGRAPHY. 
Berkeley, M. J. 

1846. Observations, botanical and physiological, on the potato murrain. Jour- 
nal, Horticultural Society, London, v. 1, p. 9-34, 2 fig. 

and Broome, G.E. 

1850. Notices of British fungi. Annals and Magazine of Natural History, s. 2, 
v. 5, no. 30, p. 464. 
Brunchorst, J. 

1887. Ueber eine sehr verbreitete Krankheit der Kartoffelknollen. Bergens Mu- 
seums Aarsberetning, 1886, p. 219-226, pi. 1. 
Evans, I. B. Pole. 

1910. Corky scab of the potato {Spongospora scabies Mass.). Transvaal Depart- 
ment of Agriculture, Farmers' Bulletin 110, 2 p., 1 pi. Also in Transvaal Agri- 
cultural Journal, v. 8, no. 31, p. 462-463. 

Fischer von Waldheim, A. A. 

1877. Apercu Systematique des Ustilaginees. . . . Paris. 51 p. 
Frank, A. B. 

1897. Kampfbuch gegen die Schadlinge unserer Feldfriichte. Berlin, p. 177. 
Gussow, H. T. 

1913. Powdery scab of potatoes, Sporigospora subterranea (Wallr.) Johnson. 
Phytopathology, v. 3, no. 1, p. 18-19, 1 pi., 1 fig. 
Horne, A. S. 

1911. On tumour and canker in potato. Journal, Royal Horticultural Society 
[London], v. 37, pt. 2, p. 362-389, fig. 96-106. 

Johnson, T. 

1907. Der Kartoffelschorf Spongospora solani Brunch. Jahresbericht, Vereini- 
gung fur Angewandte Botanik, Jahrg. 4, 1906, p. 112-115, pi. 3. 



1907. Some injurious fungi found in Ireland. Economic Proceedings, R-oyal 
Dublin Society, v. 1, pt. 9, p. 345-370, pi. 32-35. 



1908. Spongospora solani, Brunch. (Corky scab). Economic Proceedings, Royal 
Dublin Society, v. 1, pt. 12, p. 453-464, pi. 45. 



1909. Further observations on powdery potato-scab, Spongospora subterranea 
(Wallr.). Scientific Proceedings, Royal Dublin Society, n. s., v. 12, no. 16, 
p. 165-174, pi. 12-14. 

Lagerheim, G. de. 

1892. Remarks on the fungus of a potato scab {Spongospora solani Brunch). 
Journal of Mycology, v. 7, no. 2, p. 103-104. 
Martjtxs, K. F. P. von. 

1842. Die Kartoffel-Epidemie der letzten Jahre oder die Stockfaule und Raude 
der Kartoffeln . . . Munchen, 70 p., 3 pi. 
[Massee, Qeorge.] 

1908. "Corky scab" of potatoes. (Spongosjjora scabies, Mass.). Journal, Board 
of Agriculture [Great Britain], v. 15, no. 8, p. 592-599, 1 pi. 

1910. Diseases of Cultivated Plants and Trees. London, p. 98, 528, 573. 

15 



16 BULLETIN 82, L T . S. DEPARTMENT OF AGFJCULTUEE. 

Mei.hu?, I. E. 

1913. The powdery scab of potato (JSpongospora solani) in Maine. Science, n. s., 
v. 38, no. 969, p. 133. 
Morse, W. J. ■ 

1913. Powdery scab of potatoes in the United States. Science, n. s., v. 38, no. 
9G7, p. 61-62. 
Osborx, T. G. B. 

1911. SpongOBpora snbterranea, (Wallroth) Johnson. Annals of Botany, v. 25, 
no. 98, p. 327-341, pi. 27. 
Pethybridge, G. H. 

1910. Potato diseases in Ireland. Department of Agriculture and Technical 
Instruction, Ireland, Journal, v. 10, no. 2, p. 241-256, 8 fig. 



1911. Investigations on potato diseases. Department of Agriculture and Tech- 
nical Instruction, Ireland, Journal, v. 11, no. 3, p. 417-449, 14 fig. 



1912. Investigations on potato diseases. Department of Agriculture and Tech- 
nical Instruction, Ireland, Journal, v. 12, no. 2, p. 334-360, 5 fig. 



1913a. On the nomenclature of the organism causing "corky-"' or "powdery -scab" 
in the potato tuber, Spongospora subterranea (Wallroth) Johnson. Journal, 
Royal Horticultural Society [London], v. 38, pt. 3, p. 524-530. 



19136. Investigations on potato diseases. Department of Agriculture and Tech- 
nical Instruction, Ireland, Journal, v. 13, no. 3, p. 460-461. 
Wallroth, F. W. 

1842a. Der Knollenbrand der Kartoffel. Linnsea, Bd. 16, Heft 3, p. 332. 



18426. Die Xaturgeschichte der Erysibe subterranea Wallr. In his Beitrage zur 
Botanik, Bd. 1, Leipzig, p. 118-123, pi. 2, fig. 12-15. 



lS42c. [Uber die bekannte Krankheit an der Schale der Kartoffelknollen.] 
Flora, Jahrg. 25, Bd. 1, No. 8, p. 119; No. 9, p. 133. 

Q 



BULLETIN OF THE 




i 



No. 83 




Contribution from the Office of Experiment Stations, A. C. True, Director. 
April 22, 1914. 

FARMERS' INSTITUTE AND AGRICULTURAL EXTEN- 
SION WORK IN THE UNITED STATES IN 1913. 

By John Hamilton, Farmers' Institute Specialist. 

Reports on farmers' institute work for the year ended June 30, 
1913, were received from all the States except Virginia and 
Washington, the Territory of Hawaii, and the island of Porto Rico. 
Institutes were held in all the States and Territories except Louisi- 
ana, Nevada, Alaska, and Porto Rico. In Louisiana, although a 
small appropriation is made to the department of agriculture for 
institute purposes, yet no institutes were held because of the insuffi- 
ciency of the funds available. Meetings, however, of institute char- 
acter were conducted by the agricultural college and experiment 
station. Detailed data regarding institutes are given in the table 
at the end of this report (pp. 26-33) . The more important facts are 
summarized below. 

PROGRESS OF FARMERS' INSTITUTES IN 1913. 

The total number of regular institutes held in 41 States during 
the year was 7,926, of which 6,747 were general, 1,098 women's, 
and 81 young people's institutes. The total time devoted to insti- 
tutes was 10,578 days, an increase of 387 days over that reported 
lor the previous year. There was a total attendance at these insti- 
tutes of 2,897,391, an increase of 7.6 per cent over that of the pre- 
vious year. Young people's institutes were held in four States 
and covered 89 days, with an attendance of 22,100. Women's 
institutes were held in 12 States covering 1,323 days, with an attend- 
ance of 84,039 — a marked advance over the previous year. 

In addition to the regular institutes, there were various activities 
classed as special institutes, which included 187 movable schools, 
held in 13 States, occupying 949 days, with an attendance of 85,637; 
25 educational trains in 15 States, covering 24,725 miles, carrying 
422 lecturers, making 993 stops for meetings and reaching 501,523 
persons; 768 so-called independent institutes in 10 States, attended 

Note. — This publication is of interest to farmers' institute workers in the United States and Canada. 
31542°— 14 1 



2 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

by 197,848 persons; 66 "round-up" institutes in 16 States, with 
an attendance of 122,400 persons; and 346 farmers' picnics, fairs, 
conventions, etc., visited and addressed by farmers' institute lec- 
turers, with an attendance of 95,209 persons. Of the movable 
schools, 50 were for women and covered 362 days, with an attend- 
ance of 11,502; 14 were for young people, covering 70 days and 
having an attendance of 1,344. 

The total reported attendance at regular and special farmers' 
institutes in 41 States was 3,900,008 as compared with an attendance 
of 4,029,546 in 45 States reported the previous year. There was a 
falling off in the attendance upon special institutes in 1913 of 447,730, 
due to the fact that fewer educational trains were run than during 
the previous year. The average attendance per train, however, 
was larger than in 1912. In a number of States the educational 
train seems to have served its purpose as an advertising agency and 
is being replaced by the more localized and systematic forms of 
itinerant work. 

The total fund reported as available for farmers' institutes, 
$510,784, was somewhat less in 1913 than during the previous year. 
The amount reported as expended for institute purposes was $474,384, 
or an average of about $23 per institute session as compared with 
$25 the previous year. 

During the year 33 agricultural colleges and experiment stations 
furnished 415 lecturers at farmers' institutes, and 28 of these insti- 
tutions report 2,950 days of time given to institute work by their 
representatives. This shows a falling off of 59 lecturers in the num- 
ber furnished by the colleges and a reduction of 5.7 days of time for 
each lecturer during 1913 as compared with the previous year. This 
is no doubt due to the rapid expansion of the extension feature in the 
colleges which is now taking the time of college instructors and 
diverting their efforts from the institutes to the other forms of exten- 
sion work. This withdrawal, however, does not seem to have dimin- 
ished the total number of lecturers on the institute force in the 
several States, the reports showing 1,036 persons listed in 1913 as 
regularly employed by the State directors as lecturers. 

Institute directors in 13 States report that 63 of their instructors 
gave 385 days of time to teachers' institutes, meeting at these insti- 
tutes a total of 36,819 persons. Eighty-one persons gave 347 days 
of time to high-school instruction, meeting 43,191 persons. Twenty- 
five men gave 41 days to instruction in the normal schools, meeting 
16,258 persons. Forty men devoted an aggregate of 387 days to 
lecturing in the rural public schools, meeting 64,420 children. One 
hundred and twenty-five men gave 18,439 days to itinerant work 
among the farmers, giving advice and conducting demonstrations, 
and 97 men gave 1,824 days to other forms of extension work. 



farmers' institute and EXTENSION WORK, 1913. 3 

GROWTH OF THE INSTITUTES DURING THE LAST DECADE. 

The growth of the farmers' institute movement in the United States 
during the last 10 years is noteworthy. In the season of 1902-3 there 
were held 9,570 sessions of institutes in 41 States. In 1912-13 there 
were held 20,640 sessions, an increase of 115 per cent. The attend- 
ance in 1902-3 was 904,654; in 1912-13 it was 2,897,391 at the regular 
institutes, and at the special institutes 1,002,617; an increase at the 
regular institutes of 220 per cent and in all forms of institutes 331 per 
cent. The average attendance at each session increased 49 per cent, 
or from 94.53 to 141. The appropriations increased from $187,226 
to $510,784, or 172 per cent. During this period there have developed 
also the extension departments of the agricultural colleges, which last 
year reached directly about three millions of people with agricultural 
information. 

The following table shows details of the progress of farmers' insti- 
tute work from 1903 to 1913: 

Progress of the farmers' 1 institute work from 1903 to 1913. 



Year. 



Regular institutes. 



Number 

of 
half-day 
sessions. 



Number 
of States 
and Ter- 
ritories 
reporting. 



Attend- 
ance. 



Average 
attend- 
ance per 
session. 



Appropri- 
ation. 



Special in- 
stitutes, at- 
tendance. 



1903 
1904 
1905 
1906 
1907 
1908 
1909 
1910 
1911 
1912 
1913 



9,570 
10,622 
10,555 
11, 409 
11,514 
14, 934 
15,535 
16,586 
16,741 
19,430 
20,640 



904,654 
841,698 
995, 192 
1,299,172 
1,596,877 
2, 098, 268 
2,240,925 
2,395,508 
2,291,857 
2,549,199 
2, 897, 391 



94.53 
76.41 
94.28 
114. 00 
138. 80 
140. 00 
144.00 
144. 00 
138. 00 
131.00 
141. 00 



8187,226 
212,611 
225,738 
269,671 
284,450 
325,569 
345,666 
432,374 
432, 693 
533,972 
510, 784 



326, 250 

149,449 

340,414 

617, 954 

537,336 

1,323,693 

1,480,347 

1,002,617 



1,625,422 
1,746,326 
2,438,682 
2,858,879 
2,932,844 
3,615,550 
4,029,546 
3,900,008 



This table indicates a steady advance in all directions during the 
period named. The farmers' institute has shown this steady growth 
year by year, notwithstanding the rise of many other agencies for 
rural betterment that have appeared in the last decade. The inherent 
quality that has enabled the institute not only to hold the interest 
but to increase the number of its constituency until now it reaches 
annually about four millions of rural people in the United States is 
that it meets a need of rural men and women that no other agency 
has yet been able to supply, viz, a public forum where the scientist 
and the common man can meet on equal footing and discuss their 
problems face to face. 

It should be noted also that this entire movement has been initiated 
and conducted without national appropriation for its support and 
with a minimum amount of departmental aid, thus exhibiting an 



4 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

initiative vitality and capacity for service to the great body of farm- 
ers that no other institution for agricultural improvement in this 
country can boast. 

ADMINISTRATIVE METHODS. 

During the past year a request was sent out to the State farmers' 
institute directors for complete sets of their forms in use in conduct- 
ing their work — for copies of their instructions to their lecturers and 
local representatives, advertising posters, postal-card notices, etc., as 
well as forms of reports by the local managers and institute lecturers 
on the progress of the work. 

There was a very general response to the request. As was to be 
expected, the methods in use in conducting the work varied in the 
several States. Where the States were small and all localities easily 
reached the methods were extremely simple. Where, on the other 
hand, the States were large and the work correspondingly extended 
the administrative methods were more elaborate. 

An examination of these reports would seem to show that the fol- 
lowing facts underlying all institute work should be recognized in 
planning for conducting it : 

(1) That all local people should be fully informed as to the places, 
dates, and character of the institutes to be held in their community, 
and that this information should be given widely enough and far 
enough in advance to enable proper preparations to be made for 
holding the meeting successfully. 

(2) That it is due those furnishing the funds for institute support, 
whether derived from private or public sources, that the general 
public, in whose interest the money is given, should have opportu- 
nity to enjoy the advantages of the institute. In order to do this, 
the institute must be thoroughly and effectively advertised. 

(3) That this advertising can not be left to chance, but must be 
systematically undertaken and be prosecuted by individuals directly 
interested if the meetings are to be a success from the point of view 
of attendance. 

(4) That in order that the State institute director may be informed 
as to the progress of the work, reports upon the following items are 
necessary: On attendance, interest manifested, officers selected, ex- 
pense of conducting the work, plans for the ensuing year, the capa- 
bility and acceptability of the lecturers, the capability of the pre- 
siding officer, the names of influential local people in attendance, 
subjects discussed, results obtained, amounts contributed by local 
people, as well as amounts received from other sources. 

(5) Detailed information is also needed respecting instruction 
trains run, movable schools held, round-up institutes, independent 
institutes, schools aided, local assistance rendered, demonstrations 
conducted, special institutes, etc. ■ 



FARMERS* INSTITUTE AND EXTENSION WORK, 1913. 5 

(6) That the information needed at headquarters for a proper 
understanding of the institute work is the same as if the director had 
been present in person at each meeting to observe for himself, or 
information the same as is needed by the head of a department store 
or other great enterprise in order to direct it intelligently and to 
secure its efficiency and success. 

(7) Whatever letters of instruction, reports, and advertising 
methods, therefore, are necessary for securing this information satis- 
factorily and fully should be adopted and used if the director is to 
supervise his institute operations intelligently or is to be able to 
render proper account of his administration of his office and of the 
funds intrusted to his disposal for institute support. 

(8) The reports showed that several States have worked out sys- 
tems of administration and reporting that are quite complete and in 
many respects are worthy of imitation. Indiana, Michigan, Penn- 
sylvania, Kansas, Nebraska, New York, and Ohio are among the 
number. 

That there is great need of a careful study of administrative meth- 
ods, with a view to securing greater efficiency and economy in the 
use of funds available for institute purposes, is indicated by figures 
giving the cost of institutes in the United States as a whole and in 
the different States, as shown in the following table: 

Number of days and cost of institutes held in the United States in 1912. 





Days of institutes in 1912 and 
their cost. 


State. 


Days of institutes in 1912 and 
their cost. 


State. 


Days. 


Total cost. 


Average 

cost 
per day. 


Days. 


Total cost. 


Average 

cost 
per day. 




33 

65 

213 

129 

150 

23 

23 

37 

103 

48 

421 

532 

240 

451 

119 

119 

63 

138 

590 

327 

258 

314 

146 


SI. 600. 00 

1,650.00 

4,000.00 

15,000.00 

5,159.00 

819.15 

950.00 

8,000.00 

7, 500. 00 

4.900.00 

35,950.00 

18,750.00 

37,245.22 

18,000.00 

14.200.00 

3,000.00 

6,000.00 

2,751.28 

9,000.00 

25,991.22 

17,900.00 

8,750.00 

10,000.00 


$48. 48 
25.38 
18.77 

116.28 
34.39 
35.61 
41.30 

216.21 
72.81 

102.08 
85.39 
35.24 

155. 19 
39.91 

119.32 
25.21 
95.23 
19.94 
15.25 
79.48 
69.38 
27.86 
68.49 




332 

19 

51 
437 
491 

61 
682 
614 

77 
429 

28 
191 
302 

93 
744 
297 

38 
104 
204 
353 


$18,300.00 

1.600.00 

2,500.00 
27,009.00 

9,530.00 
11,000.00 
27, 400. 00 
10.500.00 

6.100.00 

25,500.00 

485.21 

3.400.00 
13,000.00 

5,000.00 
17,500.00 
11,000.00 

3,000.00 
10,000.00 

8.203.20 
19,688.89 


$55. 12 




New Hampshire 


84.21 




49.02 






61.80 


Colorado 


North Carolina 

North Dakota 

Ohio 


19.40 




180. 32 




40.16 






17.10 


Georgia 




79.22 




Pennsylvania 

Rhode Island 

South Carolina 

South Dakota 


59.44 


Illinois 


17.33 




17.80 




43.04 




53.76 






23.52 


Maine 


Utah 


37.03 


Maryland 




78.94 






96.15 


Michigan 


West Virginia 

Wisconsin 


40.21 


MinnAsnt.q. 


55.77 




Total 




Missouri 


10,089 


487,832.17 


48.35 


Montana 











This table indicates in brief that the cost per institute day varied 
widely, the average for the United States as a whole being $48.35. 
While it is true that the expenditures credited to some of the States 



6 BULLETIN" 83, U. S. DEPARTMENT OF AGRICULTURE. 

in this table were not wholly for institutes proper, a considerable 
amount going for instruction trains and similar activities, this appar- 
ently does not fully explain the great diversity shown. If the Michi- 
gan rate of $15.25 had prevailed throughout the country the number 
of institute days could have been 31,989 instead of 10,089. 

A much lower rate than that of Michigan is reported for the women's 
institutes of Ontario, namely, $3.16 per meeting, of which only $2.40 
was supplied by the provincial government, the rest being raised 
locally. The low cost of these institutes seems to be due in large 
measure to efficient organization and local initiative. District organi- 
zations coextensive with the electoral districts are supplemented by 
branch societies, each consisting of small local women's clubs through- 
out the district holding monthly meetings. The members pay annual 
dues, and other funds for club purposes and for local public improve- 
ments are raised in various ways. The strength of the organization 
is in the fact that the members live in the community, meet fre- 
quently, and are active throughout the year. They are not depend- 
ent on outsiders who come and go, as are the institutes in most of the 
States, but they are largely self-sustaining and self-reliant. The fact 
that 85 per cent of the women's institutes held in Ontario in 1912 
were conducted with comparatively little outside aid is proof of the 
fact that independence, the result of self-support, is possible in the 
farmers' institute work if proper organization is had for the pro- 
motion of this spirit. 

The need for multiplying the number of institutes in the United 
States is such at present that most careful attention to the whole 
matter of proper organization to supply this need is a paramount 
duty on the part of those who have control of the institutes in the 
several States, and the example of Canada in the conduct of its 
women's institutes and of Michigan in the conduct of its general 
institute operations are worthy of careful study. The county insti- 
tute with local branches in every community meeting monthly is the 
ideal organization both for economy and efficiency for which the 
institute directors should strive. 

The farmers' institute can no longer content itself with the simple 
discussion of agricultural topics. It is not sufficient that it be merely 
a debating society or agricultural lyceum. Moreover, it can no 
longer be an occasional visitor. It must live in the community. If 
it is to develop local forces, and that is its mission, it must be in daily 
and hourly contact with those forces. It must take up its abode 
with those whom it is to benefit, and teach, demonstrate, and guide 
in the things that it recommends. This means that permanent 
organizations must be formed in every community. 

The institute must identify itself with local people and get to work 
at once in the community if it is to survive as an educational force. 



farmers' institute and EXTENSION WORK, 1913. 7 

The statement made before the Country Life Commission of Wis- 
consin in 1911 by Mr. E. L. Morgan is unquestionably true that 
' ' after all the only forces that can deal constructively with rural life 
are the local forces developed." When this comes to be generally 
realized and appreciated by extension directors as a fundamental 
truth, efforts will be made to organize and foster societies for rural 
betterment in every community in every State. 

ASSOCIATION OF FARMERS' INSTITUTE WORKERS. 

The eighteenth annual meeting of the American Association of 
Farmers' Institute Workers was held at Washington, D. C, Novem- 
ber 10-12, 1913. Representatives were present from 32 States, 3 
of the Provinces of Canada, the District of Columbia, and the islands 
of Porto Rico and Hawaii. 

Reports upon the progress of the work were received from 39 
States and Provinces. These showed increased attendance during 
the year and general interest in the work. Reports from the various 
standing committees were presented upon the following topics: 
Institute organization and methods, institute lecturers, cooperation 
with other educational agencies, movable schools of agriculture, 
young people's institutes, and women's institutes. Each year the 
reports of the standing committees become more helpful in solving 
the difficulties that institute directors and lecturers encounter in the 
prosecution of their work. This year the committee on organization 
and methods called attention specially to the extreme importance of 
having in each unit or district a strong local organization. This was 
regarded as essential if the institute movement was to become most 
highly beneficial to the great body of agricultural people. 

The value of demonstration as a method of conveying information 
was also emphasized. 

In an extended investigation by the committee on institute lec- 
turers it was found that the average number of lecturers present at 
each institute throughout the country was 3. Fifteen States re- 
ported laboratory exercises in stock judging and household art. 
Movable schools averaged 5 days in duration with from 4 to 12 
teachers for each, the average number of teachers being 5.7. From 
20 to 25 per cent of the lecturers are employed by the year. The 
average age of greatest usefulness in an institute lecturer is between 
40 and 50 years, and it was held by all of those reporting that he 
should have had farm experience. 

The committee on cooperation with other agencies recommended 
that a local or district agricultural council should be organized to 
direct extension activities in each district, so as to coordinate the 
work and prevent overlapping. 



8 BULLETIN 83, U. S. DEPABTMENT OF AGRICULTUKE. 

The committee on institutes for women reported general expan- 
sion of institutes of this character, until now most of the State 
directors report some attention being given to home conditions and 
woman's life and work. Others report "we are just ready to start." 
Among the suggestions for the improvement of the work are trained 
neighborhood visitors, the organization of home-makers' clubs, and 
the making available of literature giving information respecting 
home improvement. 

One of the significant features of women's work is the enlarging 
of its scope to include the interests of young girls. In some States 
girls' canning clubs, bread-making clubs, athletic clubs, and literary 
clubs are being organized, all designed to arouse and hold the interest 
and activities of young girls in rural life and its pursuits. 

The committee on boys' and girls' institutes summed up its report 
as follows: States holding special junior institutes, 8; those holding 
special sessions at regular institutes, 12; those having junior aux- 
iliary institutes, 5; those holding special junior short courses, 8; 
those having junior sessions at summer short courses, 12; those having 
regular boys' and girls' club organizations, 36; those conducting 
junior correspondence courses, 8. The committee reported also 
that junior encampments seem to be growing in popularity. A 
criticism was made of the practice sometimes followed of enrolling 
large numbers in these clubs and requiring no service. It was rec- 
ommended that members of these clubs not regularly reporting at least 
once in two months should have their names dropped from the roll. 

The "program" of the meeting of the association was divided 
into four distinct groups — a general session, a special session, a 
women's session, and a round-table discussion. Eighteen papers in 
all were presented at these several meetings and discussed. 

The president, in his address, spoke particularly of the need for 
enlisting the cooperation in this institute movement of all classes of 
citizens, the town resident as well as the people of the rural districts, 
bankers and business men as well as farmers. He asserted that all 
were affected directly by the condition of agriculture, and all should, 
therefore, aid in its improvement. 

The officers elected for the coming year were: President, Edward 
Van Alstyne, Albany, N. Y.; vice president, W. J. Black, Winnipeg, 
Canada; secretary-treasurer, L. R. Taft, East Lansing, Mich.; execu- 
tive committee, A. L. Martin, Harrisburg, Pa.; T. B. Parker, Raleigh, 
N. C, and Mrs. F. L. Stevens, Mayaguez, P. R. 

EXTENSION WORK BY THE AGRICULTURAL COLLEGES. 

Data regarding extension work by the agricultural colleges in all 
of the States and Territories except Alaska, Arkansas, Colorado, 
Hawaii, Maryland, Nevada, South Carolina, South Dakota, Vermont, 



FARMERS INSTITUTE AND EXTENSION WORK, 1913. 



9 



Virginia, and Washington are summarized in the table at the end of 
this report (pp. 34-41), and in less detail in the tables below: 

Formal teaching as conducted by the extension departments of the agricultural colleges. 





Number 

in in- 
struction 
force. 


States 

re- 
porting. 


Days of 
service. 


States 

re- 
porting. 


Persons taught. 


Kinds of schools. 


Regis- 
tered. 


States 

re- 
porting. 


Unreg- 
istered. 


States 

re- 
porting 




296 

75 

26 

23 

. 97 


25 
12 
6 
7 
11 


5,436 

1,889 

1,227 

242 

942 


26 
8 
6 
7 
8 


72, 319 

7,649 
19, 669 
9,084 
5,720 


22 
12 
5 
5 

4 


100, 253 

650 

3,540 

595 

16,757 


11 


Correspondenceschools 


2 
2 




2 




5 






Total 






9,736 




114, 441 




121, 795 













Informal teaching as conducted by the extension departments of the agricultural colleges. 



Methods employed. 


Number 
engaged. 


States 
re- 
porting. 


Days of 
service. 


States 

re- 
porting. 


Places 
visited. 


States 

re- 
porting. 


Attend- 
ance. 


States 

re- 
porting. 




298 
426 
175 
113 

157 
56 
50 

359 


24 
25 
22 
28 

26 
17 
14 

12 


4,995 
6,154 
1,193 
4,570 

18,442 
2,676 
1,241 

2,372 


13 

15 
19 
17 

18 
11 
10 

10 


1,933 

4,012 
1,244 
2,057 

42,724 
498 
575 

1,644 


9 
18 
20 
11 

16 
10 
9 

10 


7,888 
590,570 
491,519 
179,133 

240,734 
312, 676 
46,486 

1,073,652 


. 




18 




20 


Rural club work 


12 


Demonstration: 


12 


In animal husbandry 

Miscellaneous extension serv- 


7 
8 

9 






Total 






41,643 




54, 687 




2, 942, 658 













Publications issued by the extension departments of the agricultural colleges. 



Character of publication. 


Number 
issued. 


States 
reporting. 


Pages. 


States 
reporting. 




413 

102, 323 

199 

19 


21 
25 
9 
7 


1,079 

3,443 

1,275 

124 


17 




26 




7 




6 






Total 


102, 954 




5,921 











Financial statement of the extension departments of the agricultural colleges reporting. 



Source of income. 



Amount. 



States 
reporting. 



State appropriations 

Local contributions 

Other sources 

Total (37 States reporting) 

Cost last year 

Appropriation 1913-14 

31542°— 14 2 



S663, 316. 00 
160,404.57 
166, 783. 63 



990, 504. 20 



761,113.53 
718, 835. 00 



10 BULLETIN 83, U. S. DEPARTMENT OF AGEICULTUEE. 

There was general expansion of the extension work of the colleges 
during the past year. The increase in number of persons engaged 
in this work was 66 and in the amount of time given to the work 
over 50 per cent, while the increased amount of time devoted by 
each person to extension work averaged 27.6 per cent. Thirty-one 
of the colleges employed 182 persons for their whole time, an aver- 
age of 5.87 persons per institute, while the number employed for 
part of their time amounted to 217. The amount of money appro- 
priated increased from $548,352.82 in 1912 to $990,504.20 in 1913. 

The days of service devoted to movable schools increased from 
2,386 to 5,436 and the registered attendance from 36,241 to 73,319. 
The States reporting correspondence schools in 1912 were 7; in 1913, 
12. The days of service devoted to this work in 1912 were 656; in 
1913, 1,889; and the number of students registered increased from 
2,162 to 7,649. 

The States reporting rural study clubs in 1912 were 2; in 1913, 6. 
The registered attendance had increased from 2,060 in 1912 to 19,669. 
The number of local advisers in 1912 was 82; in 1913 there were 298; 
itinerant lecturers had increased from 322 to 426; the places visited 
by those engaged in informal teaching in 1912 was 12,142; and the 
persons in attendance, 1,800,513; in 1913 the places visited num- 
bered 54,687; the persons reported in attendance, 2,942,652. 

The number of publications issued had increased from 1,949 to 
102,954. 

It is clear that the extension work of the agricultural colleges is 
developing very rapidly and along a wide range of effort and that 
the different institutions are endeavoring to introduce forms of serv- 
ice along extension lines that will be specially adapted to the condi- 
tions in their several States. 

SECTION ON EXTENSION WORK OF THE ASSOCIATION OF AMERICAN 
AGRICULTURAL COLLEGES AND EXPERIMENT STATIONS. 

At meetings of this section at Washington, D. C, November 12 
and 13, 1913, the following topics were discussed: (1) Organization 
in a college for extension; (2) problems confronting the agricultural 
colleges in their extension work and suggestions for meeting them; 
(3) things the college should undertake to accomplish through its 
extension division and how they should be undertaken; (4) coopera- 
tion with other agencies in agricultural extension; and (5) organiza- 
tion in a county or community for extension. The papers and the 
discussion of them are published in full in the proceedings of the 
association. 

Two very important reports were presented by committees ap- 
pointed at the Atlanta meeting of the association : One, a committee 
on organization of courses for preparation of extension workers; the 



farmers' institute and EXTENSION WORK, 1913. 11 

other, a committee on types of organization. The chairman of the 
first committee presented a set of tables showing the results of the 
investigations of the committee respecting the kind of preparation 
desired by the colleges. As to practical farm experience, the great 
majority were in favor of this experience as an accompaniment of 
collegiate training. The second table gave an outline of the courses 
of study at present required for the preparation of extension workers. 
In this English predominated, followed by natural science, studies in 
chemistry, physics, zoology, physiology, and bacteriology. By far 
the greatest attention was given to chemistry in this preparation. 
The third group related to fines of work offered by the colleges. Of 
those reporting, 37 offered work in agronomy, 36 in horticulture, 34 
in animal husbandry, 30 in soil management, 17 in farm engineering, 
32 in farm management, 27 in home economics, 31 in farmers' insti- 
tutes. In all, 17 subjects were enumerated, the number of colleges 
presenting them varying from 17 to 37. 

A permanent committee on extension organization and policy was 
appointed, consisting of W. D. Hurd, Amherst, Mass., three years; 
K. L. Hatch, Madison, Wis., two years; and G. I. Christie, Lafayette, 
Ind., one year. The following officers of the section were chosen for 
the ensuing year: President, W. D. Hurd, Massachusetts; secretary, 
E. G. Peterson, Utah; recording secretary, John Hamilton, Washing- 
ton, D. C. 

ILLUSTRATED LECTURES. 

The series of illustrated lectures issued by this office has abun- 
dantly proven its right to a place in itinerant instruction in agricul- 
ture. During the past year, from November 1, 1912, to October 27, 
1913, the 14 illustrated lectures published by the department were 
out in use 4,962 days, and a large number of applications for their 
use was refused on account of inability to supply the lantern slides 
accompanying the lectures. 

CORRESPONDENCE SCHOOLS. 

During the year two classes in correspondence work were organ- 
ized and operated in cooperation with the Pennsylvania State Col- 
lege, one for men and the other for women. The class for men con- 
sisted of 21 members and that for women of 15. The classes at the 
outset engaged to meet twice each week and to continue the study 
according to the plan outlined by this office, the work to be in charge 
of a local lay reader under the general supervision of the college of 
agriculture. 

The classes were organized by a member of the institute office 
visiting the college, and with the advice of the extension director 
locating the school, enlisting members for the courses, and selecting 
leaders to supervise the work. This department officer remained on 



12 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

the ground during most of the continuation of the school as an 
observer to see the character of the work and to note such defects 
in its operation as might occur. 

After witnessing the progress of the classes for three consecutive 
weeks this officer reports that the experiment up to that time was 
successful in every respect. The lay leaders were fully able to 
oversee the work. The members of the classes were thoroughly 
interested in the reading and practice exercises. The weekly written 
examination as reviewed by college experts showed that the students 
comprehended what they had studied, although some had difficulty 
in expressing their thoughts clearly in writing owing to their lack 
of training in this direction, The oral examinations, however, were 
uniformly good and the attendance was prompt and satisfactory. 

AID TO AGRICULTURE BY TRANSPORTATION COMPANIES. 

During the year data were collected from railroad presidents and 
industrial agents in the United States regarding the character of the 
extension work in agriculture pursued by the roads, viz: (1) Infor- 
mation giving, (2) aid in marketing products, (3) soil improvement, 
(4) demonstration work, (5) organizing agricultural associations, (6) 
operating agricultural instruction trains, (7) other activities, and (8) 
results accomplished. 

Returns were received from 57 roads. The mileage represented by 
these roads was 152,492, or 61 per cent of the mileage of the railroads 
of the United States operated in 1912. Thirty companies have 
industrial departments giving special attention to the development 
of agriculture and employ 144 men in this service. One road reports 
a force of 45 experts in the employ of the company during the entire 
year, giving attention to the development of agricultural extension 
and demonstration work. 

Twelve railroad companies each conducted one or more demon- 
stration farms. One has demonstration plats on 133 farms and 
another conducts 16 farms for demonstration purposes and still 
another cooperates with 400 farmers in demonstration work. One 
company furnishes land to farmers for use as demonstration plats. 
One road reports having organized a farm improvement department 
consisting of a manager, three assistant managers, and 29 field 
agents. There is a dairy agent with 7 assistants, and a car fitted up 
as a model farm dairy at their disposal. There is also a five stock 
agent with three assistants, and four market agents. 

Of the 57 companies reporting, 41 give particulars respecting their 
work in the dissemination of information, 29 with respect to market- 
ing, 26 on soil improvement, 22 on demonstration work, 17 in organ- 
izing agricultural associations, 41 in operating agricultural instruction 
trains, 28 enumerate other extension activities not embraced by the 



farmers' institute and EXTENSION WORK, 1913. 13 

other queries, and 26 report satisfaction with the results accom- 
plished. 

The transportation companies are evidently awake to the impor- 
tance of increasing production, partly in that it provides subsistence 
for the rapidly increasing population, but mainly in its effect upon 
the revenues of these corporations. Whatever motive may be 
assigned for the interest that they have manifested, the fact is that 
much has been accomplished by them in promoting a better agricul- 
ture and in securing cordial feeling and close cooperation between 
these companies and the individual farmer. 

AGRICULTURAL EXTENSION WORK IN FOREIGN COUNTRIES. 

In order that institute directors and lecturers may be kept informed 
the following notes by the assistant farmers' institute specialist 
showing the progress of agricultural extension in foreign countries 
during the past year are presented: 

England.- — In a memorandum recently issued by the Board of Agriculture and 
Fisheries to local authorities in England and Wales, grants are offered from a newly 
established fund known as the "development fund" for use in the furtherance of 
technical instruction in agriculture and horticulture. 

The grants are declared to be in aid first: "For the establishment of advisory coun- 
cils to be set up in each county or group of counties for the purpose of reviewing, 
governing, coordinating, or initiating schemes for providing higher agricultural edu- 
cation and educational experiments in connection therewith." Second. "For the 
provision and maintenance of buildings and lands for farm schools and farm institutes 
at which young agriculturists and others whose daily business is connected with the 
land may obtain scientific and practical instruction in the technicalities of their art." 

At each of these schools and institutes it is intended that a highly efficient staff 
shall be maintained to give short courses of instruction suited to the requirements of 
the district, and also to conduct experimental and research work 

The classes and courses of instruction which the Board of Agriculture and Fisheries 
aids are for "persons of 16 years of age or more who have finished their school educa- 
tion and are either pursuing technical studies with a view of becoming agriculturists, 
or are already engaged in agriculture and desire to improve their knowledge of the 
subject." 

Prof. T. H. Middleton in his introduction to the report states that it is clearly the 
duty both of the central and local authorities to devise means for applying to practical 
farming the knowledge provided by workers in research institutions. He states that 
until the knowledge of the laboratory has been translated into practice in the field 
the work of agricultural research is incomplete, and that all the knowledge hitherto 
obtained in research laboratories will be valueless to any particular locality until 
it has been applied by farmers to the cultivation of their land. He asks, How is 
this application of scientific discoveries to the commercial questions of the ordinary 
farm to be accomplished? Can farmers be expected to study scientific treatises? If 
farmers did study and understand the publications of research stations, could they 
afford the time and cost involved in the adaptation of the new principles to the par- 
ticular circumstances of their own farms? 

He refers to the fact that the important task hitherto of the local co mmi ttees charged 
with agricultural education has been to provide for the instruction of young persons 
up to the time when they leave school or college, or to supply itinerant teachers 
capable, as a rule, of instructing novices only. Now they will be expected to make 



14 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

provision for advising experienced farmers on the means to be adopted in applying 
scientific discoveries to practice. 

He alleges that it is a mistake to suppose that the proper way to introduce the 
results of scientific research to farmers is to spread information by means of lectures 
or leaflets; that information can be spread by these means, but not as a rule the 
results of research as first published by the research institutions; that few of the dis- 
coveries made by research workers are likely to be immediately applicable to the 
farm practice of a particular district, but must be modified before they can be utilized. 
When, however, on a particular farm the success of the new method has been estab- 
lished, neighbors will learn by imitation and the improvement may with advantage 
then be brought to the notice of others by lecturers and leaflets. 

For the purpose, therefore, of translating the results of research into successful 
practice, a highly trained scientific man is required who has special knowledge of 
some particular branch of science and a sufficient acquaintance with agriculture to 
command the respect of skillful and enlightened practical farmers. He states further 
that for the present all that is practicable is to lay the foundation of a system having 
as its object the bringing into existence of a class of well-qualified specialists who 
shall devote themselves to the service of agriculture. The first essential is that the 
specialist to be employed should really be a specialist. The second essential is that 
the persons who are to be engaged in the work of promoting agriculture should be of 
the same caliber as those who have advanced arts like medicine and engineering. 

Since no class of agricultural specialists corresponding to the medical specialist 
exists, it will be necessary to train up men for the work and, therefore, to employ 
at the outset young and inexperienced persons. For the first few years the work must 
suffer from this lack of experience, but just as well-trained young medical men quickly 
acquire experience so will these specialists who are being trained to help agriculturists. 

To be really useful either to the large farmer or the small holder the teacher must be 
a specialist, and if he is a scientific man his attainments in some branch of science 
should be high; if a practical man he must be a more skillful practitioner than the 
majority of those whom he instructs. 

This announcement of the purpose of the grants by the Board of Agriculture and 
Fisheries for the furtherance of technical instruction in agriculture and horticulture, 
and of the policy to be pursued in the expenditure of the funds, is of value to those 
who are in charge of extension work in the United States because of its careful analysis 
of the methods to be pursued and the qualifications of the individuals who are to 
disseminate the information. 

The declaration that the discoveries by the experiment stations should, first of all, 
be placed in the hands of learned scientists who have at the same time practical 
acquaintance with agriculture, for testing before these truths are given over to ordinary 
lecturers to promulgate for general adoption is worthy of serious attention. The two 
classes of extension men are differentiated as to their duties in disseminating in- 
formation. The observance of the distinction made will help to clear away some of 
the difficulties that at present embarrass institute and extension directors in this 
country in organizing their extension work. 

Algeria. — Under the direction of the Algerian Commission of Technical Agri- 
cultural Instruction, Industry and Commerce, a reorganization of Algerian agriculture 
is taking place which includes the establishing of demonstration farms in all the 
agricultural regions of the colony. 

This reorganization is of interest to extension workers in the United States because 
of its providing a method of teaching advanced agriculture by means of farms attached 
to the experiment stations for the purpose of exhibiting in a practical way and upon a 
considerable scale the results of the researches made by the stations. To these demon- 
stration farms farmers are invited to witness what has been accomplished and to re- 
ceive instruction respecting the methods employed and the cost incurred in securing 
the results. 



FARMERS ' INSTITUTE AND EXTENSION WORK, 1913. 15 

The experiment stations and the demonstration farms are to Berve for the instruction 
of the people by example and also for the propagation and dissemination by sale of the 
best varieties of seeds and tested plants. They are to conduct researches and experi- 
ments in plant and animal production, cultivation, fertilizers, and all farm and garden 
operations. These demonstration farms are by example also to teach economy and 
show how to check the many sources of waste and avoid unprofitable practices. They 
are to keep at the front in agricultural progress and set an example not in a theoretical 
but in a practical manner for the small as well as the large farmer by demonstrating the 
method of producing the largest net revenue in each case. 

Each station and demonstration farm is located so as to represent the average con- 
dition of the different soils, climatic and other conditions in the several regions, and 
at the same time be easy of access to visitors and have at least some irrigation waters, 
in order to conduct the vegetable garden and nurseries. The current farm practices 
of each region are followed, and improvements, as a result of experiments in the experi- 
ment stations, joined to each demonstration farm, will be made gradually each year 
in order that no mistakes may be made and bad examples set. The land for these 
farms is rented for a long term of years with privilege of purchase, and each farm does 
not exceed 600 acres except in the dry farming region, where it may include 1,200 
acres. 

The purely experimental portion of the farm is conducted independently of the 
demonstration portion and is not expected to be self-supporting. Each demonstration 
or model farm is self-supporting and all improvements are made out of its income. The 
Government, however, contributes the original funds with which first to stock and 
equip each experiment station and demonstration farm and makes an annual grant 
for the experimental work which is connected with each model farm and which, of 
necessity, can not be expected to be self-supporting. 

In order that there may be coordination, harmony, and systematic effort a director, 
whose salary is paid by the Government, has general charge of all the experiment 
stations and demonstration farms, and each station has a chief, whose salary is paid 
out of the annual grant to the experiment stations, while each demonstration farm 
likewise has a subdirector. The commission also employs scientists to conduct the 
expert scientific work of the stations, and expert teachers have charge of the instruc- 
tional work at the demonstration farms. 

The supreme object of all the experiment stations and demonstration or model farm 
work is the practical instruction of farmers in better and improved farm practices. 
The immediate practical instruction of those now actually engaged in farming is re- 
garded as most important since it reflects at once and directly on the production of the 
country, and the demonstration by the model farm method is deemed the quickest 
and surest method of accomplishing this end. Accordingly, farmers' meetings are held 
at frequent intervals at the model farms, and practical instruction by demonstration - 
is given to those in attendance. No theoretical instruction is attempted, and nothing 
not fully proven and demonstrated is given. The model farm thus becomes a per- 
manent agricultural exposition and demonstration school where the farmers go to see 
the things they are to learn, and to discuss them in the fields as they are conducted 
about the farm. After certain improved practices have become fully and surely 
demonstrated at the model farm, small fields on many individual farms are used to dis- 
seminate still further the information by practical demonstration under the direction 
of the central farm, but the entire actual work is there done by the farmer himself. 

During the lax or dormant season farmers' meetings are held throughout the country 
in order to interest the farmers in the demonstration farms and to sell improved seeds, 
plants, and animals from the model farms. 

Belgium. — Meetings or conferences for the instruction along agricultural lines of 
adults actually engaged in agriculture have been held for a number of years in various 
villages in Belgium by the agricultural supervisors, agricultural engineers, professors 
of agriculture, and others holding diplomas permitting them to give such instruction. 



16 



BULLETIN" 83, U. S. DEPARTMENT OF AGRICULTURE. 



The subjects discussed at these meetings include fertilizers, feeding of domestic 
animals, hygiene, dairying, cooperative association, rural law, the combating of the 
enemies of plants and animals, apiculture, poultry, and farriery. 

The following lists of meetings of adult farmers with the attendance for the last three 
years show the progress of the work. 

Meetings of adult farmers, with attendance for 3 years, 1908-1911. 



Kinds of meetings. 


1908-9 


1909-10 


1910-11 


Meetings by the agricultural supervisors: 


1,154 
SO 


1,157 
50 


1,119 




50 








57, 700 


57,800 


55,900 






Meetings during the winter: 


3,170 

49 


3,440 
53 


3,670 




55 






Total attendance 


155,330 


182,320 


201,850 






Agricultural meetings for the army: 


550 
27 


528 
23 


572 




26 








14,850 


12,144 


14, 872 






Meetings on apiculture: 


388 
26 


330 
26 


366 




26 






Total attendance 


10,088 


8,580 


10, 248 






Meetings on poultry culture: 


355 
46 


336 

44 


437 




53 






Total fi.ttenriancp, 


16,330 


14,784 


23,161 






Meetings on farriery: 


252 
31 


240 
29 


252 




28 






Total attendance 


7,812 


6,960 


7,056 






Special meetings: 


655 
50 


752 
50 


614 




60 






Total attendance 


32, 750 


37, 600 


36,840 







Sweden. — There is probably no country in the world where agricultural education 
is better organized and more appreciated than in Sweden. The farmers' schools in 
that country make provision for those actually engaged in agricultural work who can 
spare only part of the year for improving their education. There are 30 of these farm- 
ers' schools in Sweden, and they usually form a special part of the work of the 
people's high schools which provide for the general education of adults. The work 
of the farmers' schools is based on and is an extension of the general training given in 
the people's high schools. 

During the year 1909-10 the 30 schools were attended by 476 pupils, of whom 266 
paid their own fees. The number of students per school ranged from 4 to 40. The 
ages of the pupils varied from 16 to 33 years, the average being a little over 20£. The 
Government grant is from $825 to $1,100 per annum for each school, and at least an 
equal sum must be raised locally. 

A summer course in household economy for women was held from May 1 to October 
3, 1912. There were 6 special students of the average age of 20£ years working together 
with a number of ordinary high-school pupils. The practical instruction includes 
cooking, related business transactions, and baking of various kinds. Each pupil in 



farmers' institute and EXTENSION WORK, 1913. 17 

turn was responsible for the preparation and serving of a dinner. The theoretical 
instruction included the nutritive value of different foods, dietetics, food preserva-' 
tion, tests of fitness or unfitness of food for home consumption, domestic economy ,- 
cost of meals per head, care of the home, and rules of health. The pupils also received 
instruction in hygiene, chemistry, physics, bookkeeping, care of farm stock, dairying, 
sociology, singing, and gymnastics. The tuition fee for the summer course is $8.75. 

The Swedish system of education also provides for instruction in veterinary science, 
farriery, horticulture, forestry, the peat industry, fisheries, and economics; besides 
which there are itinerant agricultural schools and specially arranged schools for small 
holders. Another very interesting kind of educational work is now being developed, 
namely, instruction in the methods of canning fruits, preparation of dried fruits, jam 
making, preparation of preserves, etc., by means of traveling vans fitted up with the" 
necessary apparatus. 

Italy. — The expenses of the itinerant chairs of agriculture have been classed 
heretofore as "optional expenses," and therefore subject to cancellation by the 
provincial administrative assemblies for the communities when exceeding the limits 
of overtaxation. The statute of June 12, 1912, modifies this requirement as follows: 
"The Province and its communities which exceed the limit of overtaxation possess 
the authority to approve or register the optional expense balances with the same 
provisions by which excesses are authorized, always when such expenses are evidently 
necessary for health, instruction, beneficence, agriculture, and the conservation of 
itinerant chairs of agriculture." 

France. — The law of August 21, 1912, relating to departmental and communal 
agricultural instruction provides a director of agricultural services in each Department 
in place of the departmental chairs of agriculture established by the law of June, 1879. 
The work of this director includes: The popularization of agricultural knowledge; the 
teaching of agriculture; in the establishment of public instruction selected by minis- 
terial decree; the service of the economic and social interests of agriculture and of 
agricultural insurance and rural hygiene; agricultural information, statistics, and food 
supply; the direction of experimental fields; researches or technical missions, and in 
general, all the services to do with agriculture. The veterinary and forestry services 
and the direction of agricultural stations are not included in these duties. 

The departmental professor of agriculture shall hereafter be entitled "director of 
the agricultural services." He is assisted by one or several agricultural lecturers, 
who hold special positions, whose sphere of work is variable and comprehends all or 
part of one or several "arrondissements." These spheres may be extended still 
further in the case of specialists. By resolution of the chamber, a credit of $182,000 
was incorporated in the budget for 1912, and of this $160,000 is to provide salaries for 
these State functionaries and $22,000 is for other expenses which the Department or 
communes have to meet. 

The range of duties of the Department professors has remarkably increased. At 
present their duties may be divided into two groups: They are on one hand a kind of 
information bureau where farmers may seek advice in all matters, and on the other 
they serve as agents of the central administration for conducting investigations of the 
most varied nature. Under this latter head they must make a monthly report upon 
the general condition of agriculture in their special territory, and further upon tillage 
areas and growing and ripened crops, and finally conduct special investigations. 

The appointment of professors of agriculture has as a prerequisite the passing of a 
competitive examination under the Ministry of Agriculture, upon which the bill 
contains some provisions. The candidate must be 25 years of age, be a graduate of 
the agricultural college (Institute National Agronomique) or of one of the agricultural 
national schools with two and one-half years' curriculum and an uninterrupted two 
years' experience in agricultural administration after graduation. The appointment 
31542°— 14 3 



18 BULLETIN" 83, U. S. DEPARTMENT OF AGRICULTURE. 

and adaptation for the position of a professor of agriculture is determined by a jury, of 
whom three are practical farmers. In case of a vacancy in an agricultural directorship 
a competitive examination is announced, but the post is filled by a professor of 
agriculture who has already filled this office at least five years. These provisions do 
not, of course, apply to functionaries already in office. 

The State is responsible for the salaries of both classes. The salary of director of 
agriculture ranges in four grades, from $900 to $1,200. That of professor of agriculture 
from $560 to $800. Advancement to the next higher grade occurs after at least three, at 
most five, years. Both classes are subordinate to the Minister of Agriculture, who 
exercises supervision through general inspectors and inspectors in administrative 
matters through the governors of Departments. 

The Department must assume the office and traveling expenses of the director of 
agriculture and the professor of agriculture assigned to him. The Department or 
commune must defray the expenses of the other professors of agriculture. At least 
$240 annually for the traveling expenses must be included in the Department's budget. 

It is hoped by taking this course with regard to the position and salary of directors 
and professors of agriculture to exert a still more beneficial influence for the advance- 
ment of agriculture. As a matter of fact, the union of itinerant instruction with certain 
public functions and with the instructorship in elementary schools and normal 
institutions seems to be a measure worthy of imitation. 

Prussia.- — An editorial in the Journal of the Board of Agriculture (England), April, 
1913, number, discusses quite fully the system of agricultural education in Prussia. 
Attention is called by the writer to the fact that more and more theoretical instruction 
in agriculture is given in the schools and less of the practical. This is attributed to 
the tendency of the practical man who becomes a teacher to stereotype his subjects 
and gradually lose sight of the practical features of the work. 

This tendency is to some extent overcome by the practice of withdrawing these 
teachers from their schools during the summer and starting them out on itinerant 
work, thus bringing them for a considerable portion of each year in contact with the 
actual operations of agriculture. It is claimed that this contact with the farmer is 
not only of great advantage to the teacher and the farmer, but to the scholars in the 
schools to which the teacher returns in winter. There seems to be no doubt in the 
mind of the writer that much of the efficiency and popularity of the winter schools 
are due to the freshening influence and practical experience that the instructor has 
gained through contact during the itinerant period with farming people. 

Peripatetic work in Prussia is carried on by two distinct classes of persons: First, 
the teaching staffs of the winter schools, who devote only part of their time to peri- 
patetic service, and, second, a class who devote their entire time to this kind of work. 
The last class is employed for the most part by the Chamber of Agriculture while the 
necessary funds are supplied by the State. Their activities are not limited to the 
delivery of lectures, but they are required also to see that new ideas and inventions 
are brought to the attention of agricultural people in their respective districts. The 
effort on the part of the chambers of agriculture is to employ for this continuous service 
men who, in addition to possessing all-round knowledge of agriculture, have also 
special knowledge of some particular branch of the subject. 

In addition to the more informal methods practiced in giving instruction a large 
number of special courses on various subjects are conducted for the benefit of agri- 
culturists in all parts of Prussia. The majority of these are short, practical series of 
lectures on subjects such as bookkeeping, manures, pig breeding, etc. There are also 
courses of instruction for country women and girls in domestic economy and similar 
subjects. There is also a large amount of continuation school work carried on, also 
a system of colleges for training agricultural teachers to supply the necessary pedagogic 
skill to peripatetic teachers who possess theoretical and practical knowledge but have 
no teaching experience. 



farmers' institute and EXTENSION WORK, 1913. 19 

A very important fact is noted by the writer to the effect that there is a tendency 
on the part of the winter schools to increase in number and of the lower agricultural 
schools to decrease. This is attributed to the fact that the agricultural population, 
from whom the students are mainly drawn, appreciate the theoretical education given 
in winter, but do not appreciate the practical instruction given during the rest of the 
year, when equally good and at the same time paid practical experience can be ob- 
tained on farms. 

STATE REPORTS. 

Detailed information respecting institute work in the several States 
is given in the statistical tables accompanying this report. Numerous 
items of interest, showing the progress of the work, but which are 
incapable of tabulation, appear in the reports of the directors. In 
order that these features may be known by the body of workers, the 
principal points presented are referred to in the following accounts 
under the names of the respective States : 

Alabama. — A round-up meeting and summer school for institute workers was held 
at the Alabama Polytechnic Institute, continuing through 84 sessions, with a registered 
attendance of 900. 

Alaska. — The farmers in Alaska are so widely scattered and travel so costly that 
it is impracticable to organize or maintain farmers' institutes. There are, however, 
approximately 2,000 people in the Territory who have small gardens. In the towns 
and in some camps are market gardeners who make a success of the business. There 
are vast areas of wilderness that could be made into farms, but the director reports 
that settlement can not and will not be made until railways are built. The principal 
need at present is money to pay the salaries and expenses of traveling instructors. 

Arizona. — The special topics assigned to be discussed in every institute during the 
season were dairying, dry farming, good roads, and insect pests. The new features 
introduced into the institute work were the demonstration train, the farmers' fort- 
nightly course at the university, and the farmers' institute at county fairs. The great 
need for the development of the work is more money to increase the number of institute 
workers. 

Arkansas. — A school for boys and girls was held at the State fair and on May 31 
there was held what was called "Silo Day" at the agricultural college. Changes in 
the faculty of the college and the staff of the experiment station, together with meager 
appropriation for institute purposes, has seriously interfered with the development 
of the work. 

California. — The new features introduced into the institute work during the 
year were the formation of women's agricultural clubs, and the appointment of 
itinerant and county advisors. Owing to differences in local climates and leisure 
seasons in various parts of the State, institutes are held every month. The State 
legislature has increased the farmers' institute appropriation per annum from $15,000 
to $25,000. 

Colorado. — Many counties in Colorado have no agricultural interest, consequently 
institutes are held in a limited number only. The work is so closely combined with 
that of college extension that no well-defined line of separation exists, making it 
difficult to report separately upon these two features of extension. The failure of 
the State to pay the appropriation this year has prevented much that had been 
planned. 

Connecticut. — The farmers' institute work formerly carried on by the State board 
of agriculture, the Connecticut Dairymen's Association, and the Connecticut Pomo- 
logical Society has been combined under a single directive head. An effort is being 
made to bring the institutes into closer relations with the agricultural fairs. Several 



20 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

meetings at these exhibits have been held and arrangements are being made for the 
formation of a State association. 

Delaware. — The special topics assigned to be discussed in every institute during 
the past season in Delaware were poultry and home economics. An educational 
train was run during the first week of December over the Chesapeake and Delaware 
Peninsula, making 15 stops in Delaware and 15 in Maryland. The total attendance 
was 2,684. The topics discussed by the lecturers accompanying the train were tomato 
culture, fruit culture, live stock, corn growing, poultry, and alfalfa. 

Florida. — The new features introduced into the institute work in Florida during 
the year were county institutes and produce contests. There was a live-stock con- 
vention and a citrus seminar was held. Lectures were also given at agricultural 
fairs. The director, in answer to inquiry as to the particular assistance needed in hie 
work, replied "more publications." 

Georgia. — In Georgia the principal new feature introduced into the institute 
work during the year was the development of the county institute by organizing 
them with a full set of officers and the adoption of a constitution and by-laws. During 
the year a live-stock conference and breeders' meeting, and several horticultural 
meetings were held and a number of agricultural excursions made to the college and 
experiment station. 

Idaho. — The State has increased the appropriation for institute work from $4,000 
a year to $12,500. The number of movable schools has been increased, county agents 
have been appointed, and summer picnic institutes held in regions not easily acces- 
sible in winter. It is proposed to lessen the number of old-time farmers' institutes 
as the movable schools and county agents increase in number. There has been added 
to the staff in the field a home economics extension worker and horticultural expert. 
The subject of live stock was assigned to be discussed at every institute held in the 
State. A new feature was introduced into the work in the form of a round table 
exercise. The first session at each institute included this round table discussion. 

Illinois. — In Illinois the county institutes are independent organizations estab- 
lished by law and are assisted by the State with funds and speakers when these are 
applied for. The agricultural college and experiment station workers serve only 
when called upon. An annual convention of the farmers' institute workers is held 
each year, continuing for a week, at which the election of district directors is held. 
Provision is also made for women's auxiliaries and special features are provided by 
the institute for the instruction of young people along agricultural lines. 

Indlvna. — An annual conference was held in October consisting of six sessions; 
the average attendance of the active workers was 31, and the average attendance of 
workers and visitors together was 55. Greater emphasis is being placed upon the 
organization of boys' and girls' school clubs. 

Iowa. — In Iowa the county institute is an independent organization. The money 
is appropriated to the amount of $75 directly to each county holding an institute of 
not less than two days during the year. An annual convention is provided for, at 
which each institute organization is entitled to representation provided it has been 
organize d at least one year and has reported to the State secretary of agriculture through 
its president and secretary or executive committee that an institute was held accord- 
ing to law. In connection with the annual convention, either preceding or following 
the date on which officers are elected, the State board may hold a State farmers' 
institute for the discussion of practical and scientific problems relating to various 
branches of agriculture. 

Kansas. — The new features introduced into the institute work in Kansas during 
the past year were boys' institutes and demonstration work by county and district 
agents. The subjects taught on the railroad instruction trains were diversified farming 
and home management. Institutes, also were held in connection with orchard dem- 
onstrations. There were also dairy institutes and other meetings for special purposes 
not on the regular institute schedule. 



farmers' institute and EXTENSION WORK, 1913. 21 

Kentucky. — Corn clubs, corn judging shows, home coming rallies, and orchard 
demonstration meetings were held under the auspices of the farmers' institute. Among 
the new features was the organization of women 's home economic clubs as auxiliaries 
to the farmers' institutes. 

Louisiana. — The farmers' institute work in Louisiana is by law placed under the 
direction of the commissioner of agriculture and immigration. Owing to the meager 
appropriation no institutes have been held by this department, but meetings of similar 
character have been conducted by the director of the State experiment station at 
Baton Eouge. 

Maine. — The law in Maine requires that two institutes shall be held in each county 
each year. Considerable attention has been given during the past year to assisting 
at meetings held in the interest of cooperation among farmers and in assisting in organ- 
izing associations of this character. In addition to the regular institutes lecturers 
have been sent to 37 meetings of granges. 

Maryland. — A new feature introduced into the farmers' institutes during the year 
was the illustrated lecture. This has been found to be a very effective method of im- 
pressing agricultural truth. The illustrations are taken from Maryland farms and from 
work done at the agricultural experiment station and the college. 

Massachusetts. — This year the Massachusetts Board of Agriculture voted to amend 
the rule relating to institutes so as to require societies to hold at least one institute 
each year instead of three as in the past. The plan is to spend more money on the one 
meeting, have more and better speakers, and to advertise each meeting more thor- 
oughly. The secretary of the board is to assume immediate control and give greater 
assistance without taking the actual arrangements out of the hands of local committees. 
A summer field meeting of the board was held continuing through one day, and also a 
public winter meeting continuing for three days. 

Michigan. — The new feature introduced into the institute work during the year 
was cooperation with county agricultural advisors. Calls for new work also came in 
the form of more meetings of the women's congresses. This was insistent and the 
institutes are beginning work in this direction by holding from two to six meetings a 
year, the latter number where the organization is firmly established. The plan is to 
place in the hands of each of the congresses an outline to be followed much as study 
clubs are carried on, these to be supplemented by suggestions, questions, and helps 
from the department, and with the traveling libraries and loan collections of pictures 
from the State libraries, which are furnished without charge to such organizations . 
The topics considered at these meetings will be practical ones which affect the home 
and household, such as sanitation, cookery, scientific cleaning, canning fruits and 
vegetables, home nursing, home gardens, and such topics as the schools, preservation 
of trees, birds, public buildings, and grounds, and good roads. The department sends 
also an outside lecturer or demonstrator to at least two of these meetings during the 
year. It is planned to exchange speakers by sending members of the local congresses 
from one county to the next, thus working cooperatively. The topics treated by 
lecturers accompanying the institute trains were alfalfa, dairying, beekeeping, and 
agronomy. 

Minnesota. — In Minnesota the new feature was that of granting assistance to county 
agent work. The institute board aided nine counties in this direction, using in all 
$1,675 for this work. 

Mississippi. — The new feature introduced into institutes in Mississippi was the 
organization of farm clubs for production and market demonstration. The clubs are 
organized for growing sweet and Irish potatoes, corn, cane, and hogs, and for the coop- 
erative and systematic marketing of these products. This work is being done chiefly 
in the section devastated by the Mexican boll weevil. It is the purpose to establish 
county organizations and extend the work to every district in the State. The institute 
work in the summer begins July 1, running three months. The winter period begins 
December 1, continuing for a like period. The interim between each active season 



22 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

is spent by the department officers in correspondence, organization, planning of work, 
lecturing before schools, institutes, and normals. The topics discussed from institute 
trains were live stock, soils, and general crops. 

Montana. — The new feature introduced during the year was the inauguration of a 
farmers' week and calling a country life convention at the agricultural college. There 
were also demonstrations held at the experiment station farms under the auspices of 
the institute division. 

Nebraska. — The new feature introduced by the Nebraska institutes was fruit-tree 
pruning demonstrations. The institute authorities are also urging the one-week 
short course and expect to hold a considerable number of these next year. Special 
fruit institutes were held, and assistants was also given at farmers' club meetings. 

New Hampshire. — A summer field meeting was held continuing through two ses- 
sions with an attendance estimated at 2,000. A new feature introduced was demon- 
strations at the institutes by the use of live stock on the platform. A new law was 
enacted by the legislature in 1913 by which a department of agriculture was created 
and the State divided into three agricultural districts. In addition to the commis- 
sioner of agriculture, the governor was authorized to appoint six practical agricultur- 
ists, two of whom shall reside in each of the districts, constituting an advisory board 
of the department of agriculture. They are allowed their actual and necessary 
expenses while performing official duty and the additional sum of $4 per day. They 
are required to meet at the office of the commissioner of agriculture as often as once 
in two months to advise with him as to the work of the department. The commis- 
sioner is required to hold one or more farmers' institute meetings in each county 
annually and at least one State meeting. He is required to cooperate so far as may be 
practicable with the extension work of the college of agriculture and mechanic arts, 
and is required to provide courses of study of one week or more to be pursued in con- 
nection with the county demonstration meetings in counties offering satisfactory- 
agricultural cooperation. He is also required to cooperate with the State superin- 
tendent of public instruction in the preparation of elementary courses in agriculture 
for secondary schools, as well as courses for elementary work in the lower grades of 
the common schools. 

New Jersey. — In addition to the regular institutes held throughout the State, 
lecturers were provided for meetings for Jewish people, for Y. M. C. A. conventions, 
corn growing associations, country church clubs, county schools of agriculture, and 
agricultural clubs. 

New Mexico. — The work in New Mexico consisted almost entirely of running agri- 
cultural trains. During June, July, and August 17 of the county teachers' institutes 
were attended by the superintendent of agricultural extension and his assistant. 
Boys' and agricultural industrial club work was conducted, but chiefly through corre- 
spondence. The lack of an appropriation for institute work has limited the efforts 
of the director to the work designated. 

New York. — In one county in New York a series of lectures was given in lieu of 
the institutes. The farmers' institute bureau is cooperating with the county bureaus 
now organized in 17 counties of the State. The work of forming and supervising cow 
testing associations has been added to the duties of the farmers' institute. Twenty- 
five such associations are now in operation. Summaries of the addresses of institute 
lecturers were printed and distributed, thus permitting persons present at their 
delivery to take home for future reference the facts presented. The director of 
farmers' institutes holds conferences annually in all of the counties. At these con- 
ferences he meets representative farmers, at which time the institutes and other agri- 
cultural work for the year are arranged for. A local correspondent is selected for each 
institute, his duties being to arrange for securing a suitable hall and to assist in adver- 
tising the meeting. Special topics, lime and humus, were assigned to be discussed 
at all institutes, and in the dairy section the organization of cow testing associations. 
Approximately 450 farms were visited and spraying and other demonstrations given. 



farmers' institute and EXTENSION WORK, 1913. 23 

North Carolina. — A new feature of the work in North Carolina was the holding 
of a three-day normal or training institute for the benefit of lecturers prior to their 
starting out on institute work. This year before making up the programs or selecting 
the speakers the director wrote to members of the committees in the several com- 
munities asking them to suggest topics that would in their opinion be likely to be 
most helpful to their different localities. Two hundred and thirty-two days of 
women's institutes were held, consisting of 460 sessions and attended by 20,268 women. 
The dates, places, and programs of the institutes are arranged by the State director 
in consultation with the local committees. Thirty-five thousand reports of the pro- 
ceedings of the institutes were printed and distributed. 

Ohio.- — Under the new law the number of institutes required to be held in each 
county has been increased from four to five. The funds are distributed on the basis 
of $300 for each of the 88 counties. The dates, places, and programs of the institutes 
are arranged by the institute committee of the State board of agriculture. 

Oklahoma. — Owing to radical changes in the law, institutes have been without 
organization since January, 1913. This was brought about through a bill which 
recalled the board of agriculture and practically destroyed the institute organization. 
Institutes for women, however, were held as usual, to the number of 497, attended by 
30,922 women. The entire appropriation for women's work was $5,000. The special 
feature introduced during the year was that of home nursing and rural hygiene. 

Oregon. — In Oregon an act was passed appropriating $25,000 per annum to con- 
duct and encourage educational extension demonstrations and field work in the sev- 
eral counties of the State to include agriculture, horticulture, dairying, domestic 
science, and other industries. The several counties were also authorized to provide 
and appropriate funds for use in agricultural or farm demonstrations and field work, 
and for each dollar so provided by the county there should be the sum of $1 in addi- 
tion to the appropriation of $25,000 to be paid out of any moneys in the State treasury 
not otherwise appropriated. The total amount so appropriated to any county having 
an area of 5,000 square miles or less, not to exceed $2,000 in any one year; and to any 
large county not to exceed $4,000 in any one year. A woman has been employed for 
the domestic science and art work, one man has been employed for extension work in 
horticulture, and another is to be added for the work in animal husbandry and dairy 
production. 

Pennsylvania. — The last Legislature of Pennsylvania enacted a law providing 
for the employment by the institute director of 10 farm advisors whose duties shall be 
to visit the farmers of the State and aid them in all questions relating to farm opera- 
tions, embracing crop rotation, drainage and water supply, small fruits, market 
gardening, horticulture, animal husbandry, dairying, and poultry. An appropria- 
tion of '$40,000 for the season was made for carrying this act into effect. The leg- 
islature also increased the regular appropriation for farmers' institute work from 
$22,500 to $27,500. The following special topics were assigned to be discussed in 
every institute during the year: Poultry, dairying, horticulture, soils, and market 
gardening. An appropriation of $12.50 per day is allowed to each county chairman 
for hall rent, printing, and hotel and traveling expenses. The balance of the appro- 
priation by the State is used by the State director in paying for the services, hotel 
and traveling expenses of lecturers. 

Rhode Island. — No special appropriation was made for farmers' institute work, 
but the sum of $700 was set aside for this purpose from the fund appropriated for the 
general work of the board of agriculture. Demonstrations for controlling tree pests, 
also in pruning and spraying were held under institute auspices. The institute 
lecturers also devoted a considerable amount of time to the development of school 
garden work and in conducting industrial contests. 

South Carolina. — A new feature of the institute work in South Carolina has been 
the holding of institutes on the farms, using the stock and field crops for illustrative 



24 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

material. All of the work of instruction is by members of the faculty of the agricul- 
tural college and by demonstration agents in the various counties. 

South Dakota. — The Legislature of South Dakota increased the appropriation 
for farmers' institute purposes from $16,000 to $20,000 per annum. A ladies' auxiliary 
of the farmers' institutes has been organized and a lady has been placed in charge of 
this department. Meetings for women were held at 128 points, with a total attend- 
ance of 11,826. The special topics discussed during the year in the men's institutes 
were alfalfa and corn growing. 

Tennessee. — Institute work during the last year was confined almost wholly to 
agricultural trains. Owing to legislative entanglements no appropriation for farmers' 
institutes was made. Notwithstanding the lack of funds, however, three round-up 
or divisional institutes were held by the commissioner of agriculture, who is in charge 
of the institute work in this State. 

Texas. — In cooperation with the State entomologist the farmers' institute director 
has appointed in each district a local entomological observer to report on insect pests. 
He has also organized a large number of baby beef and boys' and girls' hog clubs. 
Special meetings were held by the pathologist and entomologist for demonstrations 
in spraying against codling moth and other insect and fungus diseases. Five insti- 
tute trains were run. The topics presented were soil mulching, seed selection, stock 
and poultry rearing, silo construction, and control of insect and fungus diseases. 

Utah. — The special topics discussed at the institutes in Utah during the past 
season were conservation of irrigation water; economy in time, energy, and labor of 
men and women. Among the new features introduced were the appointment of 
county chairmen, and the publication of synopses of addresses to be distributed 
among the audiences. An institute train was run, the subjects taught being animal 
husbandry, dry farming, and irrigation. 

West Virginia. — At the last session of the legislature a law was enacted transfer- 
ring the farmers' institute work from the board of agriculture to the control of the 
college of agriculture at Morgantown. Under the direction of the university, four 
institute trains were run, with a total attendance of 16,490. The subjects taught 
were soil improvement, poultry, and market gardening. Lecturers from the insti- 
tute force were present at teachers' institutes, high schools, and normal schools. Six 
itinerant experts were employed in field demonstration work and as agricultural 
advisors to individual farmers. These each devoted 11 months to this service. 

Wisconsin. — In Wisconsin the special topics discussed at the institutes were soil 
conservation, crop rotation, silos, cooperation, dairying, and the growing of alfalfa. 
A number of new institute lecturers were employed during the year, among whom 
was a representative of the Wisconsin Live Stock Breeders' Association. In addition 
to the instruction given by lectures at the institutes, an edition of 10,000 copies of a 
cookbook was published and distributed. 

STATE OFFICIALS IN CHARGE OF FARMERS' INSTITUTES. 

Alabama. — C. A. Cary, Alabama Polytechnic Institute, Auburn; Reuben F. Kolb, 

commissioner of agriculture, Montgomery. 
Alaska. — C. C. Georgeson, Agricultural Experiment Station, Sitka. 
Arizona. — A. M. McOmie, superintendent of farmers' institutes, Tucson. 
Arkansas. — Martin Nelson, director of farmers' institutes, Fayetteville. 
California. — W. T. Clarke, superintendent of university extension in agriculture, 

Berkeley. 
Colorado. — C. H. Hinman, director of farmers' institutes and extension, Fort Collins. 
Connecticut. — L. H. Healey, secretary State board of agriculture and director of 

advisory board of farmers' institutes, Hartford. 
Delaware. — Wesley Webb, corresponding secretary, State board of agriculture, 

Dover. 
Florida. — P. H. Rolfs, director Agricultural Experiment Station, Gainesville. 



FARMERS ' INSTITUTE AND EXTENSION WORK, 1913. 25 

Georgia. — A. M. Soule, president State college of agriculture, Athene. 

Hawaii. — Wm. Weinrich, jr., secretary and treasurer farmers' institutes, Box 583, 
Honolulu. 

Idaho. — W. H. Olin, superintendent of extension, 439 Yates Building, Boise. 

Illinois. — H. A. McKeene, secretary Illinois farmers' institutes, Springfield. 

Indiana. — W. C. Latta, farmers' institute specialist, Lafayette. 

Iowa. — A. R. Corey, secretary State board of agriculture, Des Moines. 

Kansas. — Edward C. Johnson, superintendent of farmers' institutes and demonstra- 
tions, Manhattan. 

Kentucky. — J. W. Newman, commissioner of agriculture, labor, and statistics, 
Frankfort. 

Louisiana. — E. O. Bruner, commissioner of agriculture, Baton Rouge; W. R. Dodson, 
director Agricultural Experiment Station, Baton Rouge. 

Maine. — J. A. Roberts, commissioner of agriculture, Augusta. 

Maryland. — R. S. Hill, director of farmers' institutes, Upper Marlboro. 

Massachusetts. — Wilfred Wheeler, secretary State board of agriculture, Boston. 

Michigan. — L. R. Taft, superintendent of farmers' institutes, East Lansing. 

Minnesota. — A. D. Wilson, superintendent of farmers' institutes, University Farm, 
St. Paul. 

Mississippi. — R. H. Pate, director of farmers' institutes and extension, Agricultural 
College. 

Missouri. — T. C. Wilson, secretary State board of agriculture, Columbia. 

Montana. — F. S. Cooley, superintendent of farmers' institutes, Bozeman. 

Nebraska. — C. W. Pugsley, superintendent agricultural extension, Lincoln. 

Nevada. — J. E. Stubbs, president Nevada State University, Reno. 

New Hampshire. — N. J. Bachelder, secretary State board of agriculture, Concord. 

New Jersey. — Alva Agee, director of farmers' institutes and agricultural extension, 
New Brunswick. 

New Mexico. — W. T. Conway, superintendent agricultural extension, State College. 

New York. — Edward Van Alstyne, director of bureau of farmers' institutes, Albany. 

North Carolina. — T. B. Parker, director of farmers' institutes, Raleigh. 

North Dakota. — G. W. Randlett, superintendent of farmers' institutes and exten- 
sion, Agricultural College. 

Ohio. — A. P. Sandles, president agricultural commission, Columbus. 

Oklahoma. — Miss Irma Mathews, superintendent women's institutes, Oklahoma City. 

Oregon. — R. D. Hetzel, director extension department, Corvallis. 

Pennsylvania. — A. L. Martin, deputy secretary of agriculture, Harrisburg. 

Porto Rico. — F. L. Stevens, in charge farmers' institute work, Mayaguez. 

Rhode Island. — John J. Dunn, secretary State board of agriculture, Providence. 

South Carolina. — W. W. Long, State agent and superintendent of farmers' insti- 
tutes and extension, Clemson College. 

South Dakota. — H. H. Stoner, superintendent of farmers' institutes, Highmore. 

Tennessee. — T. F. Peck, commissioner of agriculture, Nashville. 

Texas, — J. W. Neill, director of farmers' institutes, care State board of agriculture, 
Austin. 

Utah. — E. G. Peterson, director of agricultural extension, Logan. 

Vermont. — Elbert S. Brigham, commissioner of agriculture, St. Albans. 

Virginia. — J. J. Owen, director of farmers' institutes, department of agriculture, 
Richmond. 

Washington. — J. A. Tormey, head extension department, Pullman. 

West Virginia. — C. R. Titlow, director of farmers' institutes and extension, Morgan- 
town. 

Wisconsin. — George McKerrow, director of farmers' institutes, Madison. 

Wyoming. — H. G. Knight, director Agricultural Experiment Station, Laramie. 



26 



BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 





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year. 


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FAEMEES INSTITUTE AND EXTENSION WOEK, 1913. 



27 



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8,683 

398, 215 

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13,229 

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28 BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 

Financial statistics of the farmers' institutes for the year ended June 30, 1913. 





Funds appropriated. 


Cost of institutes. 




State or Territory. 


By the 

State. 


By the 
college and 

received 
from other 

sources. 


Total cost. 


Cost per 
session. 


Appropria- 
tion for 
the season 
1914. 




$600.00 


$1,000.00 


$1,600.00 


$36.36 


$1, 600. 00 


Alaska • 




2, 500. 00 
4,000.00 

15, 000. 00 
2,500.00 
900.00 
1,000.00 
7,500.00 

25, 000. 00 


398.88 
200.00 


2,898.88 
4,200.00 

15, 000. 00 
5,000.00 
1,050.00 
1, 150. 00 
7,500.00 

25, 000. 00 


161.05 
87.50 
40.00 
43.48 
16.40 
17.96 
40.32 

125.00 


4, 400. 00 
3, 750. 00 




California 


25,000.00 


Colorado 


2, 500. 00 

200.00 

1,000.00 


Conner Hrnf 






600.00 


Florida 


10,000.00 


Georgia 




Hawaii s 






Idaho 


4,000.00 
27,650.00 
10,000.00 

7,559.21 
16, 650. 00 
20,000.00 


1,000.00 


5,000.00 
27, 650. 00 
21,000.00 
39, 987. 80 
24,085.00 
10, 866. 13 


28.90 
28.80 
15.12 
37.58 
23.82 
33.95 


12, 500. 00 
24, 550. 00 


Tllinnis 


Tndiana. . . . 


i3,3oo.6o 

39,818.63 
7,435.00 
1,500.00 


10,000.00 


Iowa 


Kansas 


22,400.00 
20, 000. 00 


Kentucky 


Louisiana l 




Maine 


2,300.00 

6,000.00 

6,000.00 

8,500.00 

23,000.00 

7,500.00 

8,750.00 

10,000.00 

17, 500. 00 




1, 050. 00 

5,437.86 

2,411.51 

8,900.00 

26,557.09 

8, 700. 00 

8, 750. 00 

10, 000. 00 

17, 500. 00 


20.19 
35.54 
15.65 
7.21 
55.67 
14.26 
17.09 
36.76 
28.55 


2,300.00 
6,000.00 


Maryland 








6,000.00 


Michigan 


400.00 
3,625.00 
1,200.00 


Minnesota 


23,000.00 


Mississippi 




Missouri 




Montana 




10, 000. 00 


Nebraska 




25, 000. 00 








New Hampshire 


1,200.00 
4, 679. 12 




995.00 
4, 679. 12 


33.16 
32.95 


2,000.00 










500.00 




New York 


38,000.00 
10,000.00 

6, 000. 00 
28, 716. 76 
10, 500. 00 

2, 500. 00 
22, 500. 00 


31,641.56 
10, 000. 00 

5,769.00 
28, 716. 76 
10, 500. 00 

2,500.00 
22, 500. 00 


22.74 
10.75 
53.91 
15.70 
8.67 
22.12 
22.23 


20,000.00 


North Carolina 




12,500.00 


North Dakota 


1,185.00 


6,000.00 


Ohio 


26,400.00 


Oklahoma 




5,000.00 






2, 500. 00 


Pennsylvania 




27,500.00 


Porto Rico i 






Rhode Island 




700.00 


546. 12 
2,200.00 
16,000.00 


15.17 
10.47 
20.02 






2, 500. 00 
16, 000. 00 




South Dakota 




20,000.00 


Tennessee 








17,500.00 
10, 000. 00 


3,010.17 
775.00 


20,510.17 
10, 000. 00 


16.60 
53.48 




Utah 


10,000.00 
































6,332.02 
20,000.00 




6,332.02 

20,000.00 

200.00 


12.17 
26.04 
18.19 








20,000.00 


Wyoming 


200.00 


1,500.00 








Total 


430,837.11 


79,947.68 


474,384.02 


22.99 


360,500.00 







1 No institutes held. 



5 No report. 



farmers' institute and EXTENSION WORK, 1913. 



29 



Number of lecturers employed by the State directors of farmers' institutes and reports of 
proceedings published for the year ended June 30, 1913. 





Total 
number 

of 

lecturers 

on the 

State 

force. 


Number of 
members 
of agri- 
cultural- 
college and 

experi- 
ment-sta- 
tion staffs 
engaged in 
institute 
work. 


Number of 
days con- 
tributed to 
institute 
work by 
agricultur- 
al-college 
and experi- 
ment- 
station 
lecturers. 


Number of State lecturers 
giving agricultural instruc- 
tion at — 


Reports of pro- 
ceedings. 


State or Territory. 


Teach- 
ers' 
insti- 
tutes. 


High 
schools. 


Nor- 
mal 
schools. 


Com- 
mon 
schools. 


Pub- 
lished. 


Num- 
ber of 
copies. 


















No. 
























15 
10 
25 
34 
42 
15 
16 
23 


15 
10 
10 
34 
20 
4 
11 
23 


72 










No. 
No. 
Yes. 
No. 
Yes. 
Yes. 
Yes. 
Yes. 
















California 

Colorado 


153 


6 

14 


5 
5 


1 


4 
5 


15,000 




30 

41 

29 

361 


5,000 












3,000 










3 


1,500 




5 






500 














15 
65 

55 


7 


210 


1 


10 


1 




No. 
Yes. 
Yes. 
Yes. 
No. 
Yes. 






50, 000 




14 


76 










2,500 












3,000 




19 
8 


18 
1 


108 


6 
1 


10 
20 


1 


2 




















23 

15 
62 

42 
15 
20 
17 
17 
52 


5 

7 
18 
8 


10 
44 
29 
60 










Yes. 
No. 
No. 
Yes. 
Yes. 
No. 
No. 
No. 
Yes. 


4,500 


Maryland 
































12, 500 






6 
3 






50,000 




14 
8 
11 
18 


132 

15 
250 
101 


3 


4 


1 










3 


5 




























New Hampshire. . . 
New Jersey 


13 

8 
8 
75 
37 
12 
44 
17 


6 

7 
8 
20 
4 
8 


30 










Yes. 
No. 
No. 
Yes. 
Yes. 
Yes. 
Yes. 
Yes. 
No. 
Yes. 


1,500 










150 

80 
79 
39 


















12 




10,000 








35,000 












25,000 


Ohio 














13 

56 
8 




8 
8 


20 

7 


5 
1 


14 


5,000 




612 
50 




Pennsylvania 

Porto Rico 2 


54 


7,500 














29 
12 
12 


9 


17 








i 


No. 
No. 
No. 
Yes. 
Yes. 
No. 












































3,666 




17 
35 








5 
11 




5 

5 


20, 000 


Utah 


15 


109 


2. 
















































West Virginia 


18 
38 
2 














No. 
Yes. 
No. 




3 
2 


9 

54 










50,000 
























Total 


1,036 


415 


2,950 


57 


107 


25 


40 




304, 500 



1 No institutes held. 



2 No report. 



30 



BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 



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s 



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29,898 

28,262 

30,877 

42,777 

1,200 

1, 492 

5,771 

8,874 


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won 


N o 

o o 

00 CO 

oTco" 


4,497 
2,684 
1,250 
7,205 
81,306 
26. 050 




C0 1O 
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rt o 

O -rt-' 


2,500 
6,730 
20, 500 
10,059 
14, 403 
11,545 
75,000 
98, 760 


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32 



BULLETIN" 83, U. S. DEPARTMENT OF AGRICULTURE. 



HCXftocno 
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34 



BULLETIN 83, U. S. DEPARTMENT OE AGKICULTURE. 



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BULLETIN 83, U. S. DEPARTMENT OF AGRICULTURE. 



_ 



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BULLETIN OF THE 



No. 84 




Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
April 16, 1914. 



EXPERIMENTS WITH UDO, THE NEW JAPANESE 
VEGETABLE. 

By David Fairchild, Agricultural Explorer in Charge of the Office of Foreign 
Seed and Plant Introduction. 

INTRODUCTION. 

A decade lias passed since the udo of Japan was first proposed 
as a vegetable to be grown by Americans. This is a short time for 
the introduction of a new vegetable, when one considers that it 
means simply that at ten different times experimenters have had a 
chance to taste its blanched shoots. But it is appropriate now that 
there be put in print some account of the experiences which various 
experimenters have had with this new vegetable. 

Enough data are at hand for the production of an extensive bulletin 
on the udo, but, as much yet remains to be done, the important conclu- 
sions regarding its culture can be stated in a few paragraphs for the 
guidance of those who are interested in trying this new vegetable. 

The writer first published, in 1902, a short account of the udo 
which he wrote in Japan while traveling as Mr. Barbour Lathrop's 
explorer 1 and before he had had any opportunity to experiment 
with the plant in America. Necessarily that account lacks any back- 
ground of personal experience with the difficulties of cultivation. 

Since 1906 the writer has had growing on his own place in Mary- 
land just such a patch of udo as he is encouraging others to plant. 
(Figs. 1 and 2.) Each spring he has had the pleasure of experiment- 
ing with it in his kitchen, as well as of blanching it in the garden, 
and he can speak now regarding it with a degree of confidence not 
possessed heretofore. As a commercial proposition he has had only 
the chance of watching an experiment in California made by a large 
asparagus grower, on the Sacramento River, who has now for three 
years been .growing several acres of udo and has shipped crates of it 
to the eastern market, where, as was to be expected, he has found 
commission merchants slow to take it up. (Figs. 3 and 4.) 

1 U. S. Department of Agriculture, Bureau of Plant Industry, Bulletin 42, 1903, pp. 17-20. 

Note. — Results of experiments in Maryland. Gives methods of cultivation, preparing, 
and cooking. Adapted to New England, the Atlantic States as far south as the Caro- 
linas, the rainy region of Puget Sound, and the truck sections of California about 
Sacramento. 

32790°— 14 



BULLETIN" 84, U. S. DEPARTMENT OF AGRICULTURE. 




Fig. 1. — Plant of udo at " In the Woods," Chevy Chase, Md., Oct. 12, 1909, from seed 
planted in the spring of 1906, showing the ornamental character of the growth. 




Fig. 2. — Field of udo at Chevy Chase, Md., showing draintiles used to blanch the shoots 

in the spring. 



EXPERIMENTS WITH UDO. 




Fig. 3. 



-The first field of commercial udo in the United States, on the asparagus farm 
of Mr. M. E. Meek, Antioch, Cal. 




Eig. 4. — A crate of udo as it appeared after being shipped from Antioch, Cal., to Wash- 
ington, D. C. The shoots were blanched by mounding up the soil, and many of the 
tips were green from exposure to sunlight above the mounds. Though slightly dis- 
colored, these were of good quality when prepared for the table. 



4 BULLETIN 84, U. S. DEPARTMENT OF AGRICULTURE. 

There is no doubt that the udo is worthy of adding to our list of 
spring vegetables, for it is easily grown, its shoots are readily 
blanched, and it requires little care. A patch of it can be forced 
every spring for at least six }:ears, and probably much longer. When 
properly prepared its blanched shoots are delicious ; they have their 
own characteristic flavor, can be prepared for the table in a great 
variety of ways, and are keenly appreciated by people of discriminat- 
ing taste. Space for space, udo will yield about the same amount of 
focd for the table as asparagus and will be ready for use at about 
the same time in the spring. Possibly more labor is required to 
blanch the shoots of the udo than those of asparagus, but the udo is 
probably somewhat easier to take care of and yields sooner. 




Fig. 5. 



-Plantation of udo one season from seed at the Arlington (Va.) Field Station, 
1905. 



As an ornamental, udo has been known to nurserymen for twenty 
years or more under the name of Aralia cordata Thunb. It might 
be termed a rank-growing, shrubby perennial with a large, fleshy 
rootstock (fig. 5). It dies down each fall after the first frost and 
comes up again, much as asparagus and rhubarb do. It grows to a 
height of 10 feet or more if on rich soil, producing a very ornamental 
mass of large green leaves, and, in the late summer, long, loose 
flower clusters, sometimes 3 feet in length. The flowers attract bees 
and flies in great numbers, and as a honey plant the udo would appear 
to warrant the attention of beekeepers (fig. G). A field of udo is 
generally humming with insects. 



EXPERIMENTS WITH UDO. 



EARLY EXPERIMENTS WITH UDO. 

Siebold and Zuccarini, 1 in their Flora of Japan, called special 
attention as long ago as 1835 to the good qualities of the udo as a 
vegetable and recommended it for introduction into Europe, with 




Fig. 6. — Flowers and fruit of the udo. The flowers are visited throughout the season by 
honeybees and flies, and the dark fruit clusters are ornamental. 

the remark that " the young shoots form a delicious vegetable," as 
follows : 

This plant probably came from China, where it is employed as a sudorific; 
it is cultivated throughout Japan in the gardens and a.s a field culture. 



1 Siebold and Zuccarini. Flora Japonica, vol. 1, p. 57, 1835. 



6 BULLETIN 84, U. S. DEPARTMENT OF AGRICULTURE. 

It is cultivated essentially for its root, which has an agreeable flavor, aro- 
matic and bitter, and is eaten in winter prepared as we do the scorzonera (S. 
hispanica L. ). The young shoots form a delicious vegetable. 

As the plant grows well all over Japan, it will acclimate itself quite as 
well to our gardens ; and this is why, cultivated with us, it may increase the 
number of our fresh vegetables by the addition of one which is good, whole- 
some, and nourishing. (Free translation.) 

In that remarkable book by Paillieux and Bois, Le Potager <Tun 
Curieux, 1 the authors give their experience with udo at their gardens 
near Crosnes. They experienced such difficulty in raising the plant 
from seed that they concluded, quite erroneously, as Ave have dis- 
covered, that udo seed must be sown as soon as mature or it will not 
germinate. 

After several attempts to get living plants, dating from 1879, they 
were finally able to secure 10 of them. These grew very satisfac- 
torily in their garden and, according to their report, they obtained, 
by blanching, very appetizing-looking shoots, resembling those of 
medium-sized asparagus. Unfortunately, the taste did not strike 
them favorably. They objected to the faint suggestion of turpen- 
tine and predicted the failure of udo in Europe. 

How extensive the trials of Paillieux and Bois were the writer has 
not ascertained, but from his own experience he realizes how easy it 
is to form an unfavorable impression regarding the flavor of a new 
vegetable, and, judging from seven years of trial, in which he has 
submitted udo to the judgment of a great many people, he believes 
it is fair to conclude, since no recipes and only the barest details are 
given in their report, that the culinary trials made by these authors 
were quite inadequate to do justice to its excellent qualities. 

Notwithstanding the fact that raw potatoes, improperly blanched 
celery, raw asparagus, and raw beets are all most disagreeable to the 
taste, the tendency is to overlook this and to condemn raw udo, 
comparing it with blanched celery, when in reality it has too strong 
a flavor to be eaten without first preparing it for the table in the 
proper way. 

RELATIVES OF ' j*>0. 

There are two native species of the genus to which the udo belongs 
which resemble it quite closely in appearance — the spikenard or 
petty morel of our rich woodlands {Alalia racemosa L.) and a Cali- 
fornia species (Aralia calif omica S. Wats.). The spikenard is said 
to grow in the shade to a height of 4 or 5 feet, but a plant which 
the writer has had in his experimental garden in full sunlight for 
four years has never grown more than 3 feet high. This plant 
flowers much earlier than Aralia cordata, about the middle of July 

» Paris, 1S09, 3d eel. 



EXPERIMENTS WITH UDO. 7 

instead of in September, and is altogether a much smaller plant. 
The root is said to be pleasant to the taste and was used as an ingre- 
dient of homemade beers in colonial times. The writer has never 
had an opportunity to blanch the shoots of the plant and test them. 
The California species is considerably larger than the spikenard 
and has leaves which are of a thicker, more leathery character than 
either the udo or the spikenard. In Maryland a plant of this species 
has lived through the mild winter of 1912-13, but it gives the im- 
pression of being distinctly not hardy there. It has not yet flowered 
and is not large enough to furnish shoots for comparison with the 
Japanese species. As material for breeding, these American forms, 
and possibly the wild sarsaparilla (A. nudicaulis L.), are promising, 
and there is room here for an interesting piece of breeding work, 
since it is the vegetative portion of the plant which is used and 
asexual methods of propagation are a success. No crossing of these 
species seems to have been attempted. 

VARIETIES OF UDO. 

When first introduced into America as a garden vegetable there 
were supposed to be two varieties only, the Kan udo and the Moyashi 
udo. Although grown side by side, there never appeared to be any 
marked difference between these two kinds, and the writer is con- 
vinced that they are identical varieties, Kan udo being seedling udo 
and Moyashi udo simply forcing udo. Much the same distinction 
exists between sea kale from seed and sea kale " crowns." 

Since this first introduction, the writer's attention was called by 
Prof. Y. Kozai, director of the Imperial Agricultural Experiment 
Station, Nishigahara, Tokyo, Japan, to the fact that in Japan what 
are "really believed to be distinct strains do exist, and these have been 
given distinctive names. Through the kindness of Prof. Kozai 
these varieties were introduced and are now growing in America. 
They are S. P. I. Nos. 33250, " Yozaemon, red, early " ; 33251, " Hanza, 
late " ; 33252, " Fushiaka, node red, midseason " ; 33253. " Shiro, white, 
very early " ; 33254, " Nakate, Usu-Aka, rosy, midseason " ; and 33255, 
" Kan udo, red, extra early." The writer has grown these and forced 
them once only, and they appear to be very similar in appearance, 
but whereas seedling or Kan udo in this latitude is ready to cut in 
April, the Hanza and Fushiaka varieties are at least three weeks or 
a month later. The Yozaemon has produced its shoots at almost the 
same time as the Kan udo. The two later starting strains will pro- 
long the cutting season well into the middle of May in the latitude 
of Washington, D. C., which will be a great advantage, and it is 
probable that other characteristics will be discovered as experimenters 
become familiar with these strains. 



BULLETIN 84, U. S. DEPARTMENT OP AGRICULTURE. 



METHOD OF CULTURE. 

Much remains to be done in the working out of the most inexpen- 
sive methods of cultivating udo. Conditions of labor and materials 
are so different here from those in Japan that the methods of the 
Japanese have to be adapted to our own circumstances. The climate 
in America, at least in the Eastern States, is so different from that 
of Japan that methods of forcing used there are not applicable here. 

As a home garden vegetable the experience of the past 10 years 
indicates that the udo, when once started, is a very easy plant to 
grow. Amateurs have experienced some difficulty in growing udo 
from seed, but anyone with greenhouse or cold-frame facilities should 
have no difficulty with fresh seed if it is sown one-fourth inch deep 




Fig. 7. 



-Young udo plants as distributed to experimenters. Seedlings from seed planted 
in February should attain tins size by the first of June. 



in March or April in what is known as screened potting soil, consist- 
ing of 1 part loam, 1 part leaf soil or mold, and 1 part sand. In two 
or three weeks the seeds should be up. From the flats, the young 
seedlings can be planted out in the ground as soon as they are 3 or 4 
inches high, or they can be potted off and later set out in the field 
(fig. T). Seedlings started in boxes or flats in March will often 
grow 4 or even G feet tall the first year and will flower freely if not 
prevented from doing so, as they should be, by cutting or pinching 
out the round flower buds in midsummer. Where the question is 
not one of propagating a horticultural strain, the seedling method 
of propagation is undoubtedly the best. 

Where, however, it is desired to perpetuate a particular strain, 
udo plants may be grown from cuttings of the green shoots. To do 



EXPERIMENTS WITH UDO. 9 

this, terminal shoots should be taken when they are three-eighths 
of an inch in diameter and cut 5 inches or more long, care being 
taken to make the cut just below one of the joints, or nodes, in order 
to insure that the cuttings form a proper callus. In California, the 
head gardener of the State University, Mr. Mansell, got 80 per cent 
of his cuttings so made to grow satisfactorily. He took them in 
late summer or early fall and put them in clean sand. The writer 
has rooted cuttings of this kind in garden soil in Maryland. 

While it is possible that cuttings of the root might grow, the 
writer's experiments with them have been failures, at least unless 
a bud from the base of the stem was included in the cutting, in 
which case it grew satisfactorily. 



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Fig. 8. — General view of one-half acre plantation of udo at the Yarrow Field Station, 
near Rockville, Md. The plants set from thumb pots in the spring here averaged 
from 21 to 4 feet high in late summer. 

The udo is a coarse feeder, with great succulent roots which travel 
rapidly through loose, rich soil. They can consume astonishing 
amounts of nitrogenous manures and turn them into succulent shoots. 
Planting udo on poor, dry lands is not recommended, for, though 
it would probably live, it would make no growth there. A specially 
constructed bed, such as is often made for asparagus, is, however, not 
necessary. 

Three and a half feet apart is close enough for plants of the udo to 
stand, for as they grow older the crowns become at least a foot across. 
On very rich soil the writer has found 4 feet not too great a distance. 
When grown even with this space between them the plants will touch 
each other and make horse cultivation impossible late in the summer. 
(Fig. 8.) 



10 



BULLETIN" 84, U. S. DEPARTMENT OF AGRICULTURE. 



Seedling plants have often produced by the following spring roots 
large enough to give a small crop of shoots, but it is advisable to 
delay cutting the crop until the second year in order not to weaken the 
plants at first — following in this practice that usual with asparagus. 

THE BLANCHING OF THE SHOOTS. 

The stems of the udo when green are rank in flavor, and although 
the green shoots when pulled, peeled, and stewed are said to make 
excellent greens, it is the blanched shoots first produced in the spring- 
that form the table delicacy. The blanching of these shoots has been 
done in a variety of ways. At first the method followed was that of 
mounding up the earth over each plant in early spring, but in this 
climate it was found that the late frosts make the soil too cold, and 









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— 1 


c - jm 







Fig. 9. — Udo planting at Baddeck, Nova Scotia, showing on the right two mounds of 
earth which cover plants which were cut down in midsummer. The shoots blanched 
under these mounds were of excellent quality. While successful in the cool summer 
of Nova Scotia, this method will probably not be practicable in warmer climates. 

the shoots are slow in coming through it. (Fig. 9.) In California, 
however, on the asparagus lands near Antioch, on the Sacramento 
River, Mr. W. II. Meek has produced excellent udo by mounding up 
the hills, much as he does those of asparagus; but there the soil is 
?ilmost as light as sawdust. 

A very satisfactory method for blanching udo in a small home 
garden is to put over each hill before growth starts in the spring a 
large draintile which has one end plugged with a cement cap or 
covering. The shoots coming up inside of the tile are well blanched, 
and this method has the advantage of making it possible to examine 
the shoots at any time to see how they are coming along. It has 
at least one disadvantage, however, in that the shoots have a tendency 
to leaf out and produce a number of unopened leafstalks which take 



EXPERIMENTS WITH UDO. 



11 



away from the robust growth of the shoots. A method which has 
obviated this defect in using tiles is to put around each hill a deep 
box or small half cask from which the bottom has been removed and 
fill it with light sand or such a light material as sifted coal ashes. 
Shoots which come up through such a medium are almost free from 
the elongated leafstalks which are developed when the shoots are 
produced in the dark air chambers under the tiles. 1 Care must be 
taken in any method of mounding up or filling in dirt or ashes over 
the crowns that the shoots do not break through into the sunlight, 




Fig. 10. — The blanched shoots from a single crown of udo from which the draintile 
has just been removed. Note the slender leafstalks rising from the main stems. 
This forms an objection to the use of the draintile or any method of forcing in a 
closed air chamber. 

for as soon as they do this they become green and take on a rank, 
objectionable flavor. 

Properly grown udo shoots produced from 3-year-old plants should 
be from 12 to 18 inches long and 1 inch to 1^ inches in diameter at 
their bases (fig. 10). Such shoots ere tender throughout, with no 
trace of fiber except in the rather thick " bark," which can be easily 
removed. Naturally, if one is impatient for the very first udo shoots, 

1 Thinking to overcome this difficulty, the experiment was made of filling the tiles 
with soil before inverting them over the crowns, but the plants refused to grow up 
through this soil. 



12 BULLETIN 84, U. S. DEPARTMENT OF AGRICULTURE. 

he can cut them when only 6 inches long, but if he will wait he will 
be rewarded by getting shoots of somewhat astonishing proportions. 

In point of season the udo crop in the latitude of AVashington 
approaches that of asparagus. It is perhaps a few days earlier 
under the draintiles. If 6-inch instead of 18-inch shoots are satis- 
factory, a crop of udo can be taken ten days or two weeks earlier than 
asparagus. 

Just as with asparagus, sea kale, and endive, udo can be forced 
by packing the roots together in a trench over a layer of heating 
manure, but this method makes a very expensive vegetable of it and 
would be resorted to only by the gardeners on large estates. Shoots 
can be produced in this way in March, and doubtless also in Novem- 
ber or December. After the removal of the crop of udo shoots in 
the spring, the crowns of the plants should be completely uncovered 
and the plants allowed to grow normally throughout the summer, 
but they should not be permitted to flower unless seed is required, the 
flower clusters being pinched or cut back as the}^ form. This latter 
is not a necessary precaution, but it tends to throw the growth of 
the plants into the roots and increase the size of the shoots for the 
table the following year. 

PREPARATION FOR THE TABLE. 

The flavor of udo is distinctly aromatic, like celery or parsnip, but 
different from either. When properly prepared it is one of the most 
delicious of vegetables, but unless properly cooked it is sure to meet 
with ridicule. The reason for this lies in the fact that its stems con- 
tain a resinous substance which gives them a decided flavor of pine 
when tasted raw. There are many people who never get farther than 
this first taste and condemn udo on the spot, forgetting how disagree- 
ably raw vegetables often taste. 

It is a simple culinary practice to boil strong-flavored vegetables 
in two (or even three) waters, and this is advisable as a general 
recommendation, although when used for soup it does not appear 
to be always necessary. An hour's stay in ice water will remove 
this resin from the shoots, provided they are cut into thin slices or 
shavings. 

Little is known regarding the food value of 'udo further than that 
analyses show it to have about the same dietetic value as celery 
or asparagus. The Chinese, who are prone to ascribe mysterious 
properties to many of their foods, have given to udo, which they 
call Dotooki. Dokii quatz, or Dosjen, medicinal properties which are 
more curious than probable. 



EXPERIMENTS WITH UDO. 



13 



RECIPES. 

The following recipes for preparing udo are recommended: 

Udo on toast. — Peel the shoots and drop them into cold water. Cut them 
into 4-inch lengths. Boil them in salt water for 10 minutes, then change the 
water, adding a fresh quantity of salted water and boiling until quite soft. 




Fig. 11. — Udo on toast with cream sauce. The entire shoot can be eaten. 

Prepare a white sauce, such as is used for cauliflower or asparagus, put the 
udo in it, and allow it to simmer until thoroughly soft. Serve on toast (fig. 11) 
in the usual way. If there is too much of the pine flavor, as there may be if the 
shoots are not thoroughly blanched, a second change of water will remedy this. 




Fig. 12. — Udo as a salad. The shoots have been peeled and cut into thin shavings and 
left in ice water until the strong flavor has been removed, then dressed with a French 
dressing. 



Udo salad, — Peel the shoots, cut them into 3-inch lengths, and then split 
them into thin shavings, letting these fall into ice water as they are made. 
Allow them to soak in the water for a half hour or an hour, so as to remove 
the resinous material in them. Serve with a French dressing of pepper, salt, 
oil, and vinegar. Do not dress the shavings until just before serving, as they 
become stringy on standing in oil. (Fig. 32.) 



14 BULLETIN 84, U. S. DEPARTMENT OF AGRICULTURE. 

Udo soup. — Remove the skin from the shoots. Cut in pieces one-half inch 
long and wash thoroughly in cold water. Cook until tender and mash through 
a colander. Add a pint and a half of milk, one-half pint of cream, two table- 
spoonfuls of butter, and one tablespoonful of flour, mixing the flour and butter 
until smooth. Season with pepper and salt. (Recipe for one bunch of udo; 
enough for five persons. ) 

CLIMATIC REQUIREMENTS OF UDO. 

From the fact that udo is grown all over Japan, one might assume 
that it is adapted to a wide range of climate, but it must be borne 
in mind that Japan has an insular climate and that none of its 
plants are subjected to drought. The udo has done best in the moist 
regions of this country, especially in the New England States, 
Canada, and the Atlantic States as far south as the Carolinas, in the 
rainy region of Puget Sound, and in the trucking sections of Cali- 
fornia, about Sacramento. The fact that it dies down in the winter 
and can be coA^ered makes it possible to grow it where temperatures 
go far below zero. A temperature of — 17° F. for a few days has 
not injured it in the least. 

DISEASES OF UDO. 

Like almost every other plant, udo has its diseases. Dr. B. D. 
Halsted, of New Brunswick, N. J., has had trouble with his plants 
because a leaf spot (Colletotrichum?) attacked the foliage and did 
much damage. The writer discovered a soft rot of the roots which 
killed a number of apparently vigorous plants on the farm of the 
Department of Agriculture at Arlington, Va., the cause of which 
proved to be a sclerotium-producing fungus, the mature form of 
which has not 3 7 et been observed. These diseases, however serious 
they may seem, should not discourage the trial by thousands of 
Americans of this easily grown early-spring vegetable, which will 
thrive under so many and varied conditions. 

REASONS FOR THE INTRODUCTION OF UDO. 

The writer is not certain that from a purely money-making stand- 
point udo will prove superior in any detail or combination of details 
to vegetables which are already under cultivation in America, but it 
has a distinctive flavor, and many people are beginning to like it, as 
they have learned to like celery, asparagus, and eggplant. Notwith- 
standing its centuries of culture in the Orient, it is still a vegetable 
whose potentiality remains quite undetermined. It is highly desir- 
able that many amateurs should experiment with it and the public 
get acquainted with it in order that a sufficient demand may be cre- 
ated to encourage growers to investigate it on a sufficiently extensive 
scale to determine whether it has any really economic advantages 



EXPERIMENTS WITH UDO. 15 

over such annual crops as celery or such perennial crops as asparagus. 
It has been estimated that when grown on a large scale it would 
require much less labor than celery and that it furnishes a crop from 
seed at least a year sooner than asparagus, and there may be other 
advantages which will appear during the long process of adaptation 
through which every new plant introduction must pass before it 
becomes a real factor in the diversification of our agriculture. 

Udo has already won many adherents among those who care for 
new vegetables, and, although it can not by any means be said to be 
a well-known table vegetable, it has arrived at a point where it might 
be pushed by any careful, enterprising advertiser of fancy vegetables. 
It has been served successfully at large dinner parties in Washington 
and on the private tables of those who have their own gardens. It is 
winning its way steadily, as evidenced by the increased call for plants 
and the fact that importations of seed from Japan have become con- 
siderable, according to recent advices from an important nursery 
firm there. 

In Europe, so far as the writer is aware, udo has not made any 
headway; but this is not to be wondered at when we consider the 
conservatism it must meet there. Mr. Philippe de Vilmorin, of the 
firm of Vilmorin-Andrieux & Cie., of Paris, admits, however, that 
udo is the one Japanese vegetable which deserves to be introduced 
into cultivation in France. 



o 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914 




BULLETIN OF THE 



No. 85 




Contribution from the Bureau of Animal Industry, A. D. Melvin, Chief. 
April 27, 1914. 

(PROFESSIONAL PAPER.) 

THE COST OF PASTEURIZING MILK AND CREAM. 

By John T. Bowen, Technologist, Dairy Division. 
INTRODUCTORY. 

In the pasteurization ot inilk and cream there are two systems in 
use at the present time, known as the "holder" and the "flash" 
processes. The holder process consists in holding the milk or cream 
for about 30 minutes after it has been heated to the pasteurizing 
temperature of 140° to 150° F. ; either in the same apparatus in which 
the pasteurization takes place or in separate holding tanks arranged 
for the purpose, after which it flows to the coolers. In the flash or 
continuous process the milk or cream flows from the receiving tank 
to the pasteurizer, where it is heated to a temperature of from 160° 
to 165° F. in from 30 seconds to 1 minute, and from thence direct to 
the coolers, where it is cooled. 

It is obvious that there is more heat required to pasteurize a given 
amount of milk or cream in the latter process than in the former; 
for example, assuming that the initial temperature of the incoming 
milk is 60° F. and that in the holder process it is heated to 150° F. 
and in the flash process to 165° F., then for every 1,000 pounds of 
milk to be pasteurized by each of these processes the actual number 
of heat units required to raise the temperature of the milk to the 
pasteurizing temperature is: 

B. t. u. 1 =l,000X0.95 2 (150-60)=85,500, holder process. 
B. t. u. =1,000X0*95 (165-60)=99,750, flash process. 

It will be noted from the above figures that the flash process of 
pasteurization requires 16.6 per cent more heat to pasteurize a given 

1 B. t. u. (British thermal unit) is the quantity of heat required to raise 1 pound of pure water 1° F. at or 
near its maximum density, 39.1° F. For practical purposes, however, it may be considered the heat 
required to raise the temperature of 1 pound of water 1° F. 

2 The specific heat of milk is taken as 0.95. The specific heat of any substance is its capacity forabsorbing 
heat compared with that of water taken as unity. 

Note. — This bulletin deals with the cost of pasteurization from an engineering point of view. It con- 
tains desirable information for proprietors of creameres and milk plants and for designers and manu- 
facturers of pasteurizing apparatus. 
33347°— 14 



2 BULLETIN 85, U, S. DEPARTMENT OE AGRICULTURE. 

amount of milk than the holder process. Furthermore, the milk 
must be cooled through a correspondingly wider range. These 
figures, however, deal only with the heat absorbed by the milk, and 
do not take into consideration that radiated to the air and absorbed 
by the metal and other materials used in the construction of the 
apparatus. 

TESTS OF MILK-PASTEURIZING APPARATUS. 

The following tests were made on the pasteurizing equipment of 
five city milk plants. They were considered as representing average 
city plants. The pasteurizing equipment in each case consisted of 
heater, holding tank, regenerator, and cooler. In plants 1 and 2 the 
heater and regenerator were combined in one unit, and in plants 3, 
4, and 5 they were separate. In plant 3 the regenerator was in the 
form of an ordinary tubular cooler, and the hot milk from the holding 
tank was pumped through the coils while the cold raw milk flowed 
over the tubes. In plants 4 and 5 the regenerators consisted of 
double-pipe arrangements, the hot milk flowing through the inner 
pipe and the cold milk through the outer and therefore surrounding 
the inner pipe. 

The boilers were in good condition and were provided with exhaust 
steam feed-water heaters which heated the boiler feed water from an 
initial temperature of 60° F. to a final temperature of 180° F. The 
boiler pressure in all cases was approximately 80 pounds. The 
efficiency of the boiler and setting is assumed to be 50 per cent in all 
cases, which is believed to be a fair average. However, if there was 
a variation of 10 per cent in the estimated efficiency of the boiler and 
setting, it would affect the cost of pasteurization by approximately 
one-half of 1 per cent. It is further assumed that the coal cost $4 per 
ton (2,240 pounds) delivered in the bunker and that it had a heat 
value of 12,500 B. t. u. per pound. 

The condensed steam was caught as it came from the heater and 
weighed and its temperature taken, the average temperature being 
180° F. The pressure of the steam entering the heater was reduced 
from the boiler pressure of 80 pounds gauge to from 3 to 5 pounds. 
Therefore, the heat absorbed in the heater per pound of steam sup- 
plied was 1,155- (180-32) = 1,007 B. t. u. For the sake of simplicity 
the heat absorbed in the heater per pound of steam supplied is taken 
as 1,000 B. t. u. 

The temperatures of the milk were taken at each stage of the process 
and are recorded in Table 1, "Temperature balance." It will be 
noted from an inspection of the temperature balance that the cycle of 
operation consisted in starting with the initial temperature of the raw 
milk and raising its temperature to the pasteurizing point, about 145° 
F., then cooling the milk down to the temperature of the raw milk. 



THE COST OF PASTEURIZING MILK AND CREAM. 3 

No account was taken of the cooling below the temperature of the milk 
in the receiving vat, as this had nothing to do with the pasteurizing 
cycle. 

Based on the foregoing data and assumptions the following calcu- 
lations are made : 

Table 1. — Results of tests at five milk-pasteurizing plants. 
HEATING. 



Time of operation hours. . 

Amount of milk pasteurized pounds.. 

Amount of steam used in the pasteurizer, 

pounds 

Heat in the steam supplied direct from 

the boiler to pasteurizer B.t.u.. 

Heat in the steam required to drive the 

pasteurizing equipment B.t.u.. 

Total heat supplied by boiler for pas- 
teurizing B. t. u.. 

Heat absorbed in the pasteurizer . .do 

Total boiler horsepower developed for 

pasteurizing B. H. P.. 

Boiler horsepower per hour developed 

for pasteurizing B. H. P.. 

Total heater horsepower consumed in 

pasteurizing B. H. P.. 

Heater horsepower per hour consumed 

in pasteurizing B. H. P.. 

Milk pasteurized per boiler horsepower, 

pounds 

Milk pasteurized per heater horsepower, 

pounds 

Coal consumed for pasteurizing, pounds. . 
Milk pasteurized per pound of coal, do 



Plant number. 



40, 

2, 

2,601, 

1,006, 

3, 607, 
2, 258, 



4.366 

577 

258 
595 
259 



854 
.000 

108.3 
24.8 
67.8 
15.6 

375 

598 

578 

70 



3.216 
20, 236 

1,383 

1,593,405 

444, 704 

2,038,109 
1,383,000 

61.2 

19.0 

41.5 

12.9 

330 

487 

326 

62 



305, 

276, 

582, 
263, 



2.0 
628 

263.5 

499 

519 

018 
.500 

17.5 

8.75 

7.9 

3.9 

435 

965 
93 

82 



4.0 
29,799 

1,128 

1,299,542 

921,664 

2,221,206 
1,128,000 

66.7 

16.7 

33.9 

8.5 

446 

879 

355 

84 



3.6 
22,055 

572.7 

659,796 

829,439 

1,489,235 
572,700 

44.7 

12.4 

17.2 

4.8 

493 

1,282 
238 



COOLING. 



Cooling water required in water section 

of cooler cubic feet. . 

Refrigeration extracted by brine.. tons.. 



1,697 



960 



.46 



.206 



317 

1.701 



COSTS. 



Capital invested in pasteurizing equip- 
ment (pasteurizers, vats, coalers, etc.) . . 
Interest per day on investment at 6 


$5,332.00 

.876 

3.652 

1,000.00 

.164 

.274 
3.500 
1.032 

.848 
.480 


$3,000.00 
.493 
2.055 

800.00 

.131 

,219 
1.750 

.582 

,480 
.460 


$2,065.00 
.339 
1.414 

300.00 

.049 

.082 
1.500 
.166 

.109 
.206 


$3,470.00 
.570 
2.380 

500.00 

.087 

.137 

3.000 

.634 

.158 
1.700 


$6,250.00 
1.027 


Depreciation and repairs per day at 


4.281 


Capital invested in mechanical equip- 
ment used for pasteurizing (engine, 


700.00 


Interest per day on investment at 6 


.115 


Depreciation and repairs per day at 
10 per cent per annum 


.192 


Labor, for pasteurizing 


3.000 


Cost of coal at $4 per ton (2,240 pounds) . . 

Cost of cooling water at 50 cents per 1 ,000 

cubic feet 


.425 
.009 




.886 






Cost of pasteurizing daily supply of 
milk 


10. 826 
. .00229 
. 00313 


6.170 
. 00262 


3.865 
.00430 


8.666 
. 00251 


9.935 


Cost of pasteurizing one gallon of 


.80387 


Average cost for the five plants of 
pasteurizing 1 gallon of milk 













BULLETIN 85, U. S. DEPARTMENT OP AGRICULTURE. 



Table 1. — Results of tests at Jive milk-pasteurizing plants — Continued. 
HEAT BALANCE. 





1 


2 


3 


4 


5 




Heat 
sup- 
plied. 


Heat 
ac- 
count- 
ed for. 


Heat 
sup- 
plied. 


Heat 
ac- 
count- 
ed for. 


Heat 
sup- 
plied. 


Heat 
ac- 
count- 
ed for. 


Heat 
sup- 
plied. 


Heat 
ac- 
count- 
ed for. 


Heat 
sup- 
plied. 


Heat 
ac- 
count- 
ed for. 


Total heat in steam supplied 


P. ct. 

100. 00 
43.86 


P. ct. 

14.51 

1.92 
11.79 

43.86 

65.97 
5.81 


P. ct. 

100. 00 
41.00 


P. ct. 

14.51 

2.41 
5.09 

41.00 

64.98 
12.98 


P. ct. 
100. 00 
151.87 


P. ct. 

14.62 

5.56 
5.38 

151.87 


P. ct. 

100. 00 
124. 76 


P. ct. 

14.64 


P. ct. 

100.00 
264. 27 


P. ct. 


Heat returned by regenerator. 
Heat remaining inliquid (eon- 


14.62 


Heat required to raise tem- 
perature of initial cnarge of 












2.91 
124.76 

65.58 
16.87 




12.42 


Heat absorbed in regenerator 




264.27 


Heat absorbed in cooler in 
reducing temperature to 






47.63 
26.80 


34.39 


Loss fn radiation, exclusive of 




38.57 








Total 


143.86 


143.86 


141.00 


141.00 


251.87 


251.87 


224. 76 


224.76 


364.27 


364.27 







TEMPERATURE BALANCE. 



Raw milk °F. 

Regenerator °F. 

Rise in regenerator °F . 

Per cent rise per cent. 

Heater °F. 

Riseinheater °F. 

Per cent rise per cent. 

Total per cent rise per cent. 

Holder °F. 

Drop in holder °F. 

Percent drop per cent. 

Regenerator °F . 

Drop in regenerator °F. 

Per cent drop percent. 

Cooler °F. 

Drop in cooler °F . 

Per cent drop per cent. 

Total per cent drop per cent. 



63.50 



146.00 
82.50 



100. 00 



146.00 
8.00 
9.70 

138.00 
29.75 
36.00 

108.25 
44.75 
54. 30 

100.00 



57.86 



150. 40 
92.54 



100. 00 



150.40 
4.24 
4.58 

146.16 
34.16 
36.85 

112.00 
54.14 
58.57 

100.00 



59.40 
131.30 
71.90 
84.00 
145.00 
13.70 
16.00 
100.00 



145.00 
2.25 
2.63 

142. 75 
63.45 
74.12 
79.30 
19.90 
23.25 

100.00 



54.00 
107.50 
53.50 
60.53 
142.40 
34.90 
39.47 
100.00 



142.40 
1.33 
1.50 

141.07 
57.07 
64.50 
84.00 
30.00 
34.00 

100.00 



47.60 

124. 10 

76.50 

78.30 

145.30 

21.20 

21.70 

100.00 



143.30 
3.90 
3.99 

141.40 
83.00 
84.96 
56.00 
10.80 
11.05 

100.00 



1 Regenerator in heater. 

2 Surface cooler used as regenerator. 



3 Direct expansion coils in cooler. 

* Cooled entirely by refrigerated water. 



ECONOMY IN USE OF REGENERATORS. 

Referring to the heat balance for the foregoing plants in which 
regenerators, or heat exchangers, were used, it will be noted that 
in some cases the heat returned by the regenerator is considerably 
in excess of the total amount supplied by the heater. It should 
be borne in mind, however, that this heat is exchanged from the 
hot milk leaving the holder to the cold incoming milk, the heat 
supplied by the steam going to make up the losses; consequently 
the greater the efficiency of the regenerator the less heat is required 
from the steam. The hot milk from the holder is transferred to the 
cooler usually through the inner pipe of the regenerator; consequently 



THE COST OF PASTEURIZING MILK AND CREAM. 5 

the milk entering the heater is thus heated, while that entering the 
cooler is partly cooled, the cooler proper reducing the temperature 
to the point desired. The function of the regenerator is therefore 
to economize heat by transferring the heat from the hot to the cold 
milk. The hot milk coming from the heater flows into the holding 
vat and is here held for about 30 minutes. It then flows through 
the regenerator to the cooler, where it is cooled by water and brine 
circulation, direct expansion of ammonia in the cooler pipes some- 
times being used instead of brine. 

Just the reverse is true in the case of the cold milk; that is, the cold 
milk comes from the receiving vat, where it is at a temperature of 
about 55° F., and goes through the outer coils of the regenerator, 
where it is heated by the returning hot milk. It is obvious, therefore, 
that any heat transferred from the hot to the cold milk represents 
just so much gain in economy. If it were possible to transfer all the 
heat in the hot milk above the initial temperature of the raw to the 
cold incoming milk after the first charge had been once heated to 
the pasteurizing temperature, the heater could be dispensed with 
entirely, and the pasteurizing would go on indefinitely. This would 
constitute, however, a theoretically perfect machine, which is an 
impossibility; but the more perfect the regenerative apparatus the 
less heat will have to be supplied by the heater. The heat balance 
in test No. 5 shows that it would have taken over two and a half 
times the heat had no regenerator been used. 

In all of the foregoing tests the pasteurizing was done with live 
steam taken direct from the boiler but reduced in pressure to from 
3 to 5 pounds. Subsequent tests show that the pasteurization could 
just as well have been done with exhaust steam, and by so doing a 
load of from 8.75 to 24.8 boiler horsepower could have been taken off 
the boiler plant except in plant 1, where the exhaust steam was 
utilized for making ice in an absorption ice plant. 

Attention is invited to the saving obtained by the use of regenera- 
tors in the foregoing tests. The boiler horsepower per hour required 
for pasteurizing in tests Nos. 1, 2, 3, 4, and 5 was 24.8, 19, 8.75, 16.7, 
and 12.4, respectively. Without the regenerator, or heat exchanger, 
the boiler horsepower per hour required for pasteurizing would have 
been increased to 35.6, 26.78, 22, 37.5, and 45.1, respectively. Thus 
the average increase in fuel would have been 96.8 per cent, or practi- 
cally doubled. In addition to the direct saving in fuel due to exchang- 
ing the heat from the hot milk coming from the holding tank to the 
cold raw milk on its way to the heater, there is an average saving 
in refrigeration of approximately 60 per cent, for it is evident that 
the heat taken out of the hot milk in the regenerator takes just 
so much work off the cooler. By referring to the temperature bal- 
ance in the table it will be noted that the drop in temperature in the 



6 BULLETIN 85, TJ. S. DEPARTMENT OF AGRICULTURE. 

regenerator varied from 29 1° to 83° F., an average of 53 J ° F. In 
other words, the milk arrived at the cooler 53£° F. lower in tempera- 
ture than it would have done had no regenerator been used. 

The regenerator is an efficient piece of apparatus when viewed 
from an engineering standpoint, but it has its disadvantages when 
viewed from the bacteriological standpoint, as it is difficult to keep 
absolutely clean and sterile unless given particular attention. 

DEPRECIATION OF DAIRY EQUEPMENT. 

Owing to the rough usage to which dairy apparatus is subjected, 
having to be taken apart for the purpose of thorough cleaning after 
each operation, and to the rapid development and improvement 
in this line of apparatus, it is assumed that about four years is its 
average useful life, at which time it is either worn out or antiquated 
and must be replaced. Therefore, it has been depreciated at the rate 
of 25 per cent per annum. 

The mechanical equipment (engine, boiler, shafting, etc.) necessary 
for the operation of the pasteurizing apparatus and which has been 
depreciated at the rate of 10 per cent per annum covers only that part 
of the total equipment which is used for pasteurizing. In other words, 
the total value of the mechanical equipment of the plant is prorated 
among the various processes through which market milk passes in a 
modern city milk plant. 

TESTS OF CREAM-PASTEURIZING APPARATUS. 

Tests made on the pasteurizing equipment in creameries covered 
both the flash and the holder processes. The pasteurizing was also 
accomplished by using (1) live steam direct from the boiler, (2) ex- 
haust steam from the engine or from steam-driven pumps, and (3) hot 
water heated by the exhaust steam from the steam-driven auxiliaries. 

In calculating the heat absorbed by the cream in the following tests, 
the specific heat of cream is taken as 0.90. In this connection it is 
well to state that there seems to be very little known at the present 
time concerning the specific heat of cream. It does, of course, vary 
to a certain extent with its chemical and physical composition. At 
a certain point on the temperature scale its specific heat is greatly 
increased, apparently above unity. This is attributed, however, to 
the melting of the butterfat and a part of the absorbed heat being used 
to effect the change. 

In Table 2 are given the results of tests on the pasteurizing equip- 
ment of four creameries. The tests were made under actual working 
conditions. In tests Nos. 1, 2, and 3 the pasteurizing was done by 
employing exhaust steam and in test No. 4 five steam was taken direct 
from the boiler through a reducing valve. 



THE COST OF PASTEURIZING MILK AND CEEAM. 



TEST NO. 1. 



Referring to test No. 1, the pasteurizing was done with hot water 
which was heated by exhaust steam from five steam-driven turbine 
separators and five reciprocating steam pumps. The arrangement 
for utilizing the heat in the exhaust steam is illustrated diagrammati- 
cally in figure 1 . As it was impracticable to put a back pressure on the 
small steam turbines used for driving the separators, as would be done 
if they were allowed to exhaust under water or into a milk heater, the 
arrangement shown was resorted to. The exhaust from the separators 
and pumps was piped into the box above the water level. The hot- 
water circulating pump took the water from the box and forced it 
through the internal tubular heater and back into the box. The 
spray pipe, located in the top of the box, above the water level, was 




Ol/EXfZjcny fi/pf. 



&0#HAST~£O( 

Fig. 1.— Elementary diagram of hot water pasteurizing equipment. 

perforated with a large number of small holes through which the re- 
turn water was sprayed. The heat contained in the exhaust steam 
was taken up by the water, the equipment acting on the principle of 
the jet condenser. There was a valve placed on the end of the spray 
pipe for controlling the temperature of the water. By opening this 
valve the return water was allowed to pour out into the box without 
absorbing much heat from the steam, while, on the other hand, if the 
valve was closed all of the return water was sprayed, thereby absorb- 
ing the maximum amount of heat. The temperature of the water was 
controlled very satisfactorily by this arrangement. There was an 
overflow pipe placed in the box, as indicated, which kept the water 
at a constant level by allowing the condensed steam to overflow into 
the sewer. There was a vapor pipe on one end of the box which 



8 BULLETIN 85, U. S. DEPARTMENT OF AGRICULTURE. 

allowed the uncondensed steam to escape to the atmosphere. The ex- 
haust box was built up of cypress lumber, being about 12 inches square 
by 14 feet long. The heat contained in the exhaust steam from the 
five steam turbine driven separators and five reciprocating pumps was 
sufficient for pasteurizing 17 per cent cream at the rate of 18,360 
pounds, or 0.18 tons, per hour. This was actually done during the 
first hour of test. The initial temperature of the cream was 49.5° F., 
and it was raised to a pasteurizing temperature of 147° F., or through 
a range of 97.5° F. 

As 1 boiler horsepower is equivalent to the evaporating of 34i 
pounds of water from and at 212° F., the boiler horsepower per hour 
required for pasteurizing under the above conditions was 67.1. It is 
therefore obvious that had this exhaust steam been allowed to go to 
waste and live steam been taken direct from the boiler for pasteuriz- 
ing, the boiler capacity of the plant would have had to be increased 
by this amount, viz., 67.1 horsepower. In other words, there was a 
saving in boiler capacity, by using the heat in the exhaust steam for 
pasteurizing, of 67.1 horsepower. As has been previously explained, 
it was necessary to employ some such arrangement as that illustrated 
in the diagram in order to avoid putting a back pressure on the turbine 
separators, although tliis arrangement entailed a loss of heat due to 
the double heat transfer from the exhaust steam to the water and from 
the water to the cream. 

Assuming that the boiler and furnace efficiency was 50 per cent 

and that the coal used had a heating value of 12,500 B. t. u. per 

pound, then the fuel saved per hour with this arrangement is 

67 1 X 34 5 X 970 4 

— T o\nn'v -n =359 pounds. If the pasteurizing equipment is 

run 4 hours a day for 310 days in the year, the annual saving in 

359 X 4 X 310 

fuel is — — fttttt: = 198.7 tons, which at $4 per ton would amount 

2,240 r 

to S794.80. In addition to the fuel saved, there is a further saving 
due to the decreased boiler capacity of the plant. 

It is evident that if the exhaust steam from the separators and 
pumps had been allowed to escape it would have been necessary 
to have taken live steam from the boilers for the purpose of pasteur- 
izing, and this would have taken an additional 70-horsepower boiler, 
which would have cost approximately $14.75 per boiler horsepower 
installed, or $1,032.50. Figuring the interest on the money invested 
at 6 per cent per annum and depreciation and repairs at 10 per cent, 
there is a saving in addition to the fuel of $165.45, making a total 
saving of $794.80 + $165.45 = $960.25, to say nothing of the increased 
labor of firing the boiler. Adding this to the actual cost would 
bring the cost of pasteurizing 100 pounds of cream in this particular 
plant up to $0.0512, or an increase of 12.3 per cent. The fuel cost, 



THE COST OF PASTEURIZING MILK AND CREAM. 9 

however, is practically doubled when steam is taken direct from the 
boiler for pasteurizing instead of utilizing the exhaust steam. The 
steam pressure is reduced from boiler pressure to about 3 pounds by 
some form of reducing valve, consequently there is approximately as 
much heat in the exhaust steam from the engine, or steam-driven 
auxiliaries, as there is in steam taken from the boiler. The amount 
of fuel mentioned above is for pasteurizing, and is not to be confused 
with the total amount used in firing the boilers. In other words, 
it is the fuel required to evaporate in the boiler a certain amount 
of water which is used for the purpose of pasteurizing the cream. 
With this arrangement the pasteurizing was done with heat that 
would otherwise have been wasted, and furthermore it took a load of 
67.1 horsepower off the boiler plant. 1 

TESTS NOS. 2, 3, AND 4. 

Tests Nos. 2 and 3 were also made with exhaust steam, but the 
arrangements were different from the foregoing, as the exhaust 
from the engines was piped directly into the heater. The only 
load on the engines at the time was the pasteurizers and the centrif- 
ugal cream separators, which amounted to very little. The exhaust 
steam available, however, was sufficient to operate the pasteurizers 
up to their full capacity. 

Referring to the summary of the tests in Table 2 it will be noted 
that the fifth item, "Heat in steam required to drive pasteurizing 
equipment," is blank except for test No. 4. The reason for this 
is that the engine or steam-driven auxiliaries from which exhaust 
steam was used for pasteurizing are considered in the light of pressure- 
reducing valves, the mechanical power being, so to speak, a by- 
product. That is to say, there is a loss of heat in steam due to drop in 
pressure, and while the wire drawing of the steam through the valve 
will superheat the steam to a certain extent, the loss may be con- 
sidered the same for the purpose of this paper, regardless of whether 
this drop is caused by passing through a pressure-reducing valve or 
through a steam engine. In test No. 4 the steam used for pasteuriz- 
ing was reduced in pressure by a valve, consequently the energy 
represented by the difference in pressure and temperature of the 
steam before and after passing through the reducing valve is a 
clear loss. In neither case, however, was the heat lost due to drop 
in pressure of the steam available for heating the cream. The 
380,800 B. t. u. in column 4 represents the heat in the steam at 
boiler pressure which was used in the engine for driving the pasteur- 
izer, separator, shafting, etc., required in the process of pasteurizing, 
and as the exhaust from the engine was allowed to go to waste it is 

!The use of exhaust steam for other purposes in milk plants is treated in Bureau of Animal Industry 
Circular 209. 



10 



BULLETIN 85, U. S. DEPARTMENT OP AGRICULTURE. 



obvious that the 380,800 B. t. u. represented so much additional 
heat over the exhaust-steam systems in tests Nos. 1, 2, and 3. 

As stated above, in test No. 4 the pasteurizing was done by live 
steam from the boiler instead of exhaust steam, and by referring 
to the tabulated results of tests it will be noted that the over-all 
thermal efficiency of test No. 4 is only 43.7 per cent while that of 
tests Nos. 1, 2, and 3 is 69.1, 60.6, and 69.7 per cent, respectively* 
although the thermal efficiency of the heater in test No. 4 was the 
greatest. 

The over-all efficiency is here taken as the ratio of the heat supplied 
by the boiler to the steam to that absorbed by the cream. 

The thermal efficiency of the heater is the ratio of the available 
heat in the steam supplied to the heater to that absorbed by the 
cream. 

HEAT BALANCE. 

No heat balance is given in Table 2 because the pasteurizing 
equipments in tests Nos. 1, 2, and 3 were installed in market cream 
plants, that is, plants whose business consisted in the handling 
and marketing of cream. The cream as received from auxiliary 
creameries was first run through separators, the result being a 
heavy cream containing about 40 per cent fat. This heavy cream 
on the way to the coolers was mixed with skimmed milk in the correct 
proportion to produce a cream containing a predetermined amount 
of fat. In view of the methods employed in these plants, it was 
impractical to get out a heat balance showing the distribution of 
heat in the pasteurizing cycle. 

Table 2. — Results of tests of four cream-pasteurizing plants. 
HEATING. 





Plant No. 




1 


2 


3 


4 


Time of operation hours. . 


3.53 


1.733 


1.5 


1.166 


Amount of cream pasteurized pounds. . 


50, 683 


6,928 


5,019.5 


4,571 




5,589.5 


1,088 


647.5 


629 


Heat supplied by boiler to steam, 80 pounds pressure, 










B. t.u.. 


6, 437, 646 


1,253,478 


746,003 


617,113 


Heat in steam required to drive pasteurizing equipment, 










B.t. u.. 








380,800 




5,589,500 


1,088,000 


647,500 


529,000 


Total boiler horsepower developed for pasteurizing, 










B.H. P.. 


193.2 


37.6 


22.4 


80.9 


Boiler horsepower per hour developed for pasteurizing, 










B.H. P.. 


54.7 


21.7 


14.9 


25.6 


Total heater horsepower consumed for pasteurizing. do 


167.7 


32.6 


19.4 


15.9 


Heater horsepower per hour consumed for pasteurizing, 










B.H. P.. 


47.5 


18.8 


13.0 


13.6 




262 


184 


224 


153 


Cream pasteurized per heater horsepower do 


302 


212 


258 


287 


Coal burned in pasteurizing do 


1,030 


200 


119 


160 


Cream pasteurized per pound of coal do 

Total U. t. u. absorbed dv cream B. t. u.. 

The over-all thermal efficiency of pasteurizing equip- 


49.2 


34.6 


42.2 


29.0 


4, 447, 433 


760,030 


520, 171 


436,176 










ment per cent.. 


69.1 


60.6 


69.7 


43.7 


Thermal efficiency of heater do 


79.4 


69.8 


80.3 


82.5 



THE COST OF PASTEURIZING MILK AND CREAM. 



11 



Table 2. — Remits of tests of four cream-pasteurizing plants — Continued. 

COOLING. 





Plant No. 




1 


2 


3 


4. 


Cooling water used in water section of cooler, .cubic feet. . 
Ice used in cooling cream to its original temperature, 


1,877 
3.44 


704 
.92 


169 
.83 


148 
1.72 







COSTS. 



Capital invested in pasteurizing equipment (pasteurizer, 


$7, 400. 00 

1.233 

5.068 

1,350.00 

.222 

.370 

10.000 

1.839 

.938 

3.440 


SI, 255. 00 

.206 

.586 

1, 000. 00 

.164 

.274 
2.000 
.357 
.352 
.920 


1600.00 

.098 

.411 

500.00 

.082 

.137 
2.000 
.203 
.084 
.830 


$700. 00 


Interest per day on investment at 6 per cent per an- 


.115 


Repairs and depreciation per day at 25 per cent per 


.489 


Capital invested in mechanical equipment used for pas- 


800.00 


Interest on investment per day at 6 per cent per an- 


.131 


Repairs and depreciation per day at 10 per cent per 


.219 




2.000 


Cost of coal at $4 per ton (2,240 pounds) 


.285 




.074 
1.720 








23. 110 
. 00378 
.0456 

.00634 

.0756 


4.857 
.00582 
.0701 


3.845 
. 00636 
.0765 


5.033 




.00939 




.1101 


Average cost of pasteurizing 1 gallon of cream in the 




Average cost of pasteurizing 100 pounds of cream in 

















TEMPERATURE BALANCE. 



42 



Temperature of raw milk °F . 

Temperature of milk in heater °F. 

Rise of temperature in heater °F. 

Total per cent rise per cent. 

Temperature of milk in holder °F. 

Drop of temperature in holder °F. 

Per cent drop in holder per cent. 

Temperature of milk in separator °F. 

Drop of temperature in separator (milk) °F. 

Per cent drop in separator (milk) .per cent. 

Drop of temperature in separator (cream) C F. 

Per cent drop in separator (cream) per cent. 

Temperature of milk in cooler °F. 

Drop of temperature in cooler (milk) °F . 

Per cent drop in cooler (milk) per cent. 

Temperature of cream in cooler °F. 

Drop of temperature in cooler (cream) °F. 

Per cent drop in cooler (cream) per cent. 

Total per cent drop do. . . 



49.5 
147.0 

97.5 
100 



42.0 
169.6 
127.6 
100 



39.3 
160.2 
120.9 
100 



56.25 
167.25 
111.00 
100 



147.0 

3.0 

3.1 

144.0 

9.2 

9.4 

12.8 

13.2 

134.8 

85.3 

87.5 

131.2 

81.7 

83.7 

100 



169.6 

U6.8 

3 13.2 

152.8 

7.2 

5.6 

15.3 

12.0 

145.6 

103.6 

81.2 

137.5 

95.5 

74.8 

100 



160.2 

1.8 

1.5 

5.0 

4.1 

158.4 

119.1 

98.5 

155.2 

115.9 

95.9 

100 



167. 25 
111.00 



1 No holder. 

2 No holder or separator. 



3 Large drop in holder was due to stirring apparatus. 



The summary of the tests in Table 2 gives the cost of pasteurizing 
at the different plants under the conditions at which each particular 
plant was operating at the time of the test. Therefore the cost of 
pasteurizing 100 pounds of cream will vary slightly in the different 
plants due to the varying conditions. It will be noted from an 
inspection of the temperature balance that the initial temperature 
of the raw cream varied in the different plants and also the final or 
pasteurizing temperatures. In order to make a comparison of cost 



12 BULLETIN 85, U. S. DEPARTMENT OF AGRICULTURE. 

it becomes necessary to put them all on an equal basis, so far as it is 
possible to do so, and for this purpose it is assumed that the pasteur- 
izing cycle consisted in raising and lowering the temperature of the 
cream through a range of 100° F., all other conditions remaining the 
same. The cost of pasteurizing 100 pounds of cream in the different 
plants, corrected as above, is $0.0459, $0.0650, $0.0726, and $0.1056 
for tests Nos. 1, 2, 3, and 4, respectively. 

The amount of cream handled will, of course, affect the unit cost 
to a great extent, as may be gathered from the summary of tests. 

Referring to test No. 4, the power required for driving the pasteur- 
izing equipment was excessive, as a considerable amount of line 
shafting was uselessly driven while pasteurizing. This, together with 
taking steam from the boiler through a reducing valve instead of 
using the heat from the exhaust steam, accounts for the high cost of 
pasteurizing at this plant. 

CONCLUSIONS. 

The conclusions drawn from the foregoing tests are as follows : 

1. The flash process of pasteurization requires approximately 17 
per cent more heat than the holder process. There is a correspond- 
ingly wider range through which the milk or cream must be cooled, 
both adding extra cost to the pasteurizing cycle. 

2. The proper design and arrangement of the heater, regenerator, 
cooler, piping, and refrigerating apparatus have much to do with the 
efficient operation of the plant. 

3. With poorly arranged apparatus and leaky piping the loss in 
heat may reach approximately 30 per cent of that required to pas- 
teurize, which it is practicable to reduce to a negligible amount. 

4. It is practicable to use exhaust steam from the engine and 
steam-driven auxiliaries, or water heated by exhaust steam, to 
furnish heat with which to pasteurize both milk and cream. 

5. Usually there is sufficient heat in the exhaust steam which is 
allowed to waste in milk plants and creameries to do the pasteurizing. 

6. For every 400 pounds of milk pasteurized per hour with exhaust 
steam, approximately one horsepower is taken off the boiler plant. 

7. The average cost of pasteurizing 1 gallon of milk is shown to be 
$0.00313. 

8. The average cost of pasteurizing 1 gallon of cream is shown to be 
$0.00634, or $0.0756 per 100 pounds. 

9. It must be understood that the cost of pasteurizing as figured 
in this paper deals only with the pasteurizing cycle, viz, starting with 
the initial temperature of the raw milk and raising its temperature 
to the pasteurizing point, then cooling the milk down to the initial 
temperature of the raw milk. In other words, it has been attempted 
to show the additional expense encountered in producing pasteurized 
milk and cream over the raw product. 

o 




BULLETIN OF THE 







No. 86 



Contribution from the Forest Products Laboratory, Forest Service 

Henry S. Graves, Forester. 

March 14, 1914. 

(PROFESSIONAL PAPER.) 




TESTS OF WOODEN BARRELS. 

By J. A. Newlin, 
Engineer in Charge of Timber Tests. 



OBJECT OF THE TESTS. 

The object of the tests described in this bulletin, made in coopera- 
tion with the Bureau for the Safe Transportation of Dangerous 
Explosives, was to obtain data upon which specifications and changes 
in the design of wooden barrels used in the transportation of danger- 
ous liquids might be based. The tests do not offer any comparisons 
between barrels made of different material or of different species of 

timber. 

MATERIAL. 

The barrels used in the test were made by the St. Louis Cooperage 
Co., and were received in six groups of 8 barrels each (48 in all) as 
follows : 



Group 
No. 


Barrel No. 


Thickness 

of staves 

and heads. 


Number 
of hoops. 


1 

2 
3 

4 
5 
6 


lto8 
la to 8a 

9 to 16 
9a to 16a 
17 to 24 
17a to 24a 


Inches. 

% 
% 
% 


6 

8 
6 
8 
6 
8 



The barrels were made from quarter-sawed white oak. (One stave 
which seemed to be particularly porous was identified as red oak.) 
The material was practically straight grained and free from defects. 
The barrels were of excellent workmanship and were well coated 
with paraffin on the inside. The staves varied in width from 
about 2\ inches to about 7 inches. Thirty-one barrels had 19 staves 
each, 12 had 20 each, and 4 had 21 each. The heads were usually 

Note. — This bulletin describes tests that are of special interest to barrel manufacturers and to manu- 
facturers and shippers of dangerous liquids. 
32797°— 14 



2 BULLETIN 86, U. S. DEPARTMENT OF AGRICULTURE. 

composed of four pieces, though two heads were each composed of 
three pieces. The pieces of the head were joined together with 
^-inch hickory dowels. There were two dowels per joint, each 
about one-third or one-fourth the length of the joint from its end. 

The head and bilge hoops were If inches by 17 gauge, while the 
quarter hoops were 1£ inches by 18 gauge. The average thick- 
nesses of hoops used for tension tests (see p. 4) were 0.051 inch 
and 0.061 inch for the 18 and 17 gauge, respectively, while the U. S. 
standard gauges of these numbers are 0.05 inch and 0.05625 inch. 

The average hoop spacing, dimensions, weights, and capacities of 
the barrels are shown on figure 1 . The hoop splices were always 
placed over the bung stave, and the heads were placed with their 
end grain toward tins stave as shown in I and II, figure 1 . 

The barrels were received at the laboratory on November 24, and 

were stored in a closed and unheated shed until the tests were begun 

on December 10. 

BARREL TESTS. 

The barrels were brought hi from the storage shed shortly before 
the time for test. Each barrel was then carefully inspected and the 
hoops driven tight by a representative of the St. Louis Cooperage 
Co. Just before test each barrel was completely filled with water, and 
with the exception of those barrels to which a pressure gauge was 
attached, was closed with a wooden bung. These bungs, after soaking 
for a few seconds in warm water, were driven to a tight fit. They 
were placed with their grain parallel to that of the staves. The bungs 
bore the brand "U. S. Bung Mfg. Co., Cincinnati, O." No bung 
straps were used. 

Two barrels of each group were tested in side compression, two in 
diagonal compression, one each in side and diagonal drop, and two 
by internal pressure. 

SIDE-COMPRESSION TESTS. 

In this test the barrel was placed between two flat surfaces and 
compressed in the direction of its diameter. The rate of compression 
was 0.25 inch per minute. Simultaneous readings of load, com- 
pression, and loss of water from the barrel were taken. The test 
was discontinued when one-half the water had escaped. Notes were 
made of the character and sequence of failures. In about one-half 
of these tests a pressure gauge was attached to the barrel, and read- 
ings of internal pressure were taken. The method of test is shown 
in Plate I. 

DIAGONAL-COMPRESSION TEST. 

In this test the barrel was compressed between two flat surfaces, 
being supported upon one point of the chime and loaded at a point 
on the other and diagonally opposite. The rate of compression was 
0.25 inch per minute. Notes were taken as in the side compression 
test. The test on the first barrel of each group was discontinued as 



'§ 







77T ~ MADE-UP SAffREL -EIGHT HOOPS 



Pounds 


Capacity 


Pounds 


G0//O/1S 


63.9 


4£4J 


J0.8 



md diagonal-drop tests " C " was the top point. Outside diameters of all 
! 24.9 inches; average diameter at the head was 21.2 inches. 




I - CT/4NMRD 3/X-//OOP BAPPEl 



TT - 3TAHDAPD E/6//r-f/OOP BAPPEL 



Wcbntss 
Mchis 


WeyAf 
Pounds 


Copecity 


founds 


G«//°"s 




64.8 

7/.0 

7?.a 


427.2 

42/. J- 

4/7.9 


S/.2 
SO.S 

JO./. 



Th/cftneSs 


Wt,sM 


Copac/ry 


P&unds 


£Wi,„s 




67.4 

74.e 

22.6 


426.7 
420.4- 

4/7.3 


J/.2 
S0.4 
J0.O 



.///. ~ MADE-UP BARREL -EJ6//r HOOPS 



Weight 
Pounds 


Cmpactfy 


founds 


Gm//ans 


62.? 


424/ 


JO.8 



i placed with plane A B D (I) wrl ic;;l. In the side-compression and side-drop tests ■' B " was the top point. In the diagonal-compression and diagonal-drop tests " C " was the top point. Outside diameters of all 
3 being about one-third inch in bung diameter and about one-tenth inch in diameter ut the head. Average bung diameter wan 24.9 inches; average diameter at the head was 21.2 inches. 



82797°— 14. (To face page 2.) 



TESTS OF WOODEN BARRELS. 3 

in the preceding test, while the second was discontinued whenever 
one-half the contents had escaped or would have escaped had the 
barrel been in the reverse position. This test is illustrated in 
Plate II. 

SIDE-DROP TEST. 

In this test the barrels were dropped on a wooden platform about 
3j inches thick resting on the concrete floor of the laboratory. On 
top of this platform was a steel plate one -eighth inch in thickness. 
The barrel was suspended with its axis horizontal. The first drop 
was 3 inches, the next 6 inches, etc., increasing each time by 3 inches. 
Each drop was upon the same point of the barrel. After the first 
apparent leak the drops were made at 3-minute intervals. The 
weight of the barrel and contents was taken immediately before 
each drop. The test was continued until half the contents of the 
barrel had escaped. Complete notes were made to show the character 
and sequence of the failures. A picture of this test is shown in 
Plate III. 

DIAGONAL-DROP TEST. 

This test was conducted in the manner described for the side-drop 
test, except that the barrel was suspended so that the lowest point of 
the chime was directly below the center of the barrel, which was 
dropped on the chime. Each drop was upon the same point. A 
picture of this test is shown in Plate IV. 

INTERNAL-PRESSURE TEST. 

In this test the barrel and connecting pipes were filled with water in 
such a way as to exclude as nearly as possible all air. The pressure 
was then raised to 2 pounds per square inch and held for 2 minutes. 
It was then raised to 4 pounds and there held for 2 minutes. This 
was repeated, increasing the pressure 2 pounds each time and holding 
it constant for 2 minutes after each increase, until 1 pound of water 
ran from the barrel in 1 minute or less. The test was then discon- 
tinued. Complete notes were made as to the character and sequence 
of the failures. 

In these tests connection to the barrel was made by screwing a 
special tapered bush into the bunghole. The apparatus is shown in 
Plate V. 

MINOR TESTS. 

STAVE TESTS. 

In order to find out something of the variability of the barrel 
material tests were made on 36 staves, two from each of 6 ban-els of 
each thickness. The best and poorest appearing stave of each barrel 
was chosen. Pieces 2 inches in width, cut from these staves, were 
tested in static bending under center loading. The span was 28 
inches. The staves were placed with the outer side up. 



BULLETIN 86, U. S. DEPARTMENT OF AGRICULTURE. 



HOOP TESTS. 



A 14-inch piece was taken from one hoop of each gauge from each 
of three barrels of each group. These pieces were machined down to 
have a parallel section approximately 1 inch by 9 inches, and were 
then subjected to tension tests. The maximum load and load at 
yield point, as determined from the drop of the scale beam of the 
testing machine, were recorded. 

RESULTS. 

BARREL TESTS. 

The results of the barrel tests are given in Tables 3 to 6, inclusive. 

The internal-pressure readings on the barrels to which a pressure 
gauge was attached in the side-compression test have been omitted. 
The highest internal pressure developed in these barrels was 7 pounds 
per square inch. 

In all the test only two or three cases of leakage at the bung was 
observed. These also have been omitted from the tabulated results. 



MINOR TESTS. 



The average, maximum, and minimum results of the stave and hoop 
tests are given in Tables 1 and 2. In Table 1 "modulus of rupture" 
is the fiber stress at maximum load and represents the strength of the 
timber. "Work to maximum load" is proportional to the shock- 
resisting ability of the timber. 

Table 1. — Results of stave tests. Static bending, 28-inch span. 



f-inch staves. 



Aver- Maxi- Mini- 
mum, mum. 



|-inch staves. 



Aver- Maxi- Mini- 
mum, mum. 



J-inch staves. 



Aver- Maxi- Mini- 
age, mum. mum. 



Measured thickness at stave, 
inches 

Rings per inch . . 

Specific gravity 

Moisture per cent.. 

Maximum load pounds. . 

Deflection at maximum load, 
inches 

Modulus of rupture, pounds 
per square inch 

Work to maximum load, 
inch-pounds per cubic 
inch 



0.G9 

15 

0.672 

10.4 

257 

2.31 



0.71 

29 

0.848 

14.1 

395 

5.20 

17,950 



0.528 
8.1 
100 



0.88 
4,290 



0.77 

14 

0.694 

9.8 

378 

1.98 

13,260 

10.0 



0.80 

25 

0.820 

13.5 

490 

3.50 

17,460 



0.74 

8 

0.558 

7.3 

220 

1.22 

8,220 



0.89 

21 

0.663 

12.6 

387 

1.90 

10, 120 



0.91 

30 

0.723 

14.8 

510 

3.50 

12,860 



0.87 

14 

0.544 

10.0 

240 

1.10 

6,330 

3.8 



Table 2. — Results of hoop 


tests. Tension, specimens 1 inch ivide. 






18-gauge hoops. 




L7-gauge hoo 


is. 




Average. 


Maximum. 


Minimum. 


Average. 


Maximum. 


Minimum. 


Measured thickness of hoops, 


0.051 

2,360 
3,955 

44,580 

74,210 


0.058 

2,900 
4,530 

49,500 

78,600 


0.047 

2,100 
3,580 

41,200 

70,200 


0.061 

2,480 

4,925 

39,515 
78,060 


0.063 

2,620 
5,130 

42,400 

82,400 


0.058 


Loadat yield point as determined 

by drop of beam pounds.. 

Maximum load do 

Fiber stress at yield point, pounds 


2,330 

4,605 

36,000 


Fiber stress at maximum load, 


71,600 







Bui. 86, U. S. Dept. of Agriculture. 



Plate I. 




Method of Test— Side Compression. 



Bui. 86, U. S. Dept. of Agriculture. 



Plate II. 




Method of Test— Diagonal Compression. 



Bui. 86, U. S. Dept. of Agriculture. 



Plate III. 




Method of Test— Side Drop. 



Bui. 86, U. S. Dept. of Agriculture. 



Plate IV. 




Method of Test— Diagonal Drop. 



Bui. 86, U. S. Dept. of Agriculture. 



Plate V. 




TESTS OF WOODEN BARRELS. 5 

GENERAL OBSERVATIONS OF NATURE OF FAILURES. 

In each kind of test the first water to appear on the outside of the 
barrel was usually from the seepage through the pores of the wood 
at the chime. The first leak usually occurred either between the 
staves and the head or between the staves at the chime. In all the 
tests except the internal pressure the first leak was usually coincident 
with the slipping of the staves. 

In the internal-pressure test there were two general classes of 
failures: (1) By springing and breaking of the head; and (2) by 
leaking between the staves at the bilge. 

In the diagonal-compression test the failure was a general failure 
of the head combined with the slipping of the staves. In the com 
pression-perpendicular test the failure was a general leaking at the 
heads and slipping of the staves followed by the breaking of the 
staves at the bilge. 

In the side-drop test the slipping of the staves caused loosening of 
the hoops and leakage at the heads. This was followed by breaking 
of the staves at the bilge. In three of the six tests the failure of the 
barrels was due to the heads being broken or forced out by the 
internal pressure produced by the impact. 

The lower heads of all barrels tested by dropping on the chime were 
broken or forced out by the pressure due to the impact. 

CHANGES IN DESIGN AS INDICATED BY THE CHARACTER OF THE 

FAILURES. 

A slight increase in the length of the chime from croze to the end of 
the stave would lessen the amount of seepage without any marked 
increase of liability to breakage at the croze by dropping the barrel 
on the chime. The chimes of the test barrels were made exceptionally 
short (three-fourths of an inch from outer side of croze to end of stave) 
to reduce the danger of breakage when dropped on the chime. Chimes 
1 inch long would probably have given better results. 

The internal-pressure test and the side-drop test indicated that the 
bilge hoops were too wide apart. A spacing of not more than 8 inches 
between the bilge hoops would have materially strengthened the bar- 
rels for the internal pressure without any weakening for the other tests. 

The weakest parts of the barrels were the heads. The first leak in 
most of the tests was due either to the springing of the head or to the 
slipping of the staves at the head, or to both these causes. 

The ultimate failure of a large per cent of the barrels was at the head. 
It appears that a head much thicker than the staves would give mate- 
rially better results. Heads should probably be made about one and 
one-half times as thick as the staves. 

The heads appeared to be materially weakened by the dowel holes 
and not infrequently the flagging was forced out. It would seem that 
these head joints could be improved. 



6 BULLETIN" 86, U. S. DEPARTMENT OF AGRICULTURE. 

None of the hoops failed during the test. A f-inch oak barrel 
should probably have not less then eight hoops of the sizes of those 
used on the barrels tested, as the swelling of the wood might break 
the hoops. 

Variation in strength of barrels of the same design is due in large 
measure to the variability of the wood composing the head and 
staves. Test specimens taken from these barrels show that some of 
the staves may have less than one-fourth the strength of others. (See 
Table 1, p. 4.) Evidently no attempt had been made to grade the 
staves on the basis of strength, the only criterion of fitness being that 
the staves should be clear and straight grained. The dry weight per 
cubic foot of clear straight-grained wood is a splendid guide as to 
probable strength, the heavier, denser wood being the stronger. The 
advisability of grading staves and heading with reference to the 
strength might well be considered. 

TESTS OF MADE-UP BARRELS. 

BARRELS. 

In order to try out the effect of some of the changes in design as 
suggested above, barrels were made up with f -inch staves, f-inch head, 
and eight hoops. The staves and hoops were from the two 8-hoop, 
f-inch barrels, the heads from f-inch barrels and previously tested 
under internal pressure. In order to make these heads fit, it was 
necessary to joint fifteen-sixteenths inch off of one stave of each 
barrel. The bilge and quarter hoops were not changed, but were 
permitted to drive farther onto the barrels. The head hoops were 
shortened H inches and were driven flush with the ends of the staves. 
(In the original tests the head hoops were driven beyond the ends of 
the staves, as shown in I and II of fig. 1 .) The spacing of the hoops, 
weight, capacity, etc., of these barrels are shown in III, figure 1. 
In assembling the barrels the hoop joints were placed at random. 

INTERNAL-PRESSURE TESTS. 

The two made-up barrels were tested under internal pressure. The 
results of these tests showed them to be fully equal to the barrels 
with f-inch heads and staves. One of these barrels withstood a 
pressure of 34 pounds per square inch up to the time the head began 
to fail, when the pressure was released. The increased capacity of 
the barrel under this pressure, due primarily to the springing of the 
heads, was 8} pounds of water. On release of the pressure the barrel 
resumed its original form with no apparent leakage. 

The head of the second barrel was broken out by a pressure of 38 
pounds per square inch. 

Neither of these made-up barrels showed any leakage between the 
staves during the tests. 



TESTS OF WOODEN BARRELS. 7 

DROP TESTS. 

The broken heads of the made-up barrels were replaced by other 
f-inch heads, and the barrels subjected to drop tests. The barrel 
dropped upon the side showed much better resistance than the 8-hoop 
barrel five-eighths inch in thickness throughout, but was not quite 
the equal of the f-inch barrels. 

In dropping on the chime the made-up barrel was the equal of any 
barrel tested. 

These tests of made-up barrels seem to justify the previously sug- 
gested changes in thickness of head and spacing of hoops. 

The detailed results of these tests are given in Table 5. 

SUGGESTIONS REGARDING TESTS OF SHIPPING CONTAINERS. 

There are two classes of tests to which containers such as barrels 
may be subjected: 

First. Tests, such as the ones described in this bulletin, where the 
object is to determine the most economical and efficient designs. 
Tests of this class are usually carried to the destruction of the con- 
tainer and entail damage or complete loss of contents. It is neces- 
sary to fill the containers with material which is relatively inexpensive, 
safe to the investigators, and which will produce stresses similar in 
character to those which would be produced by the commodity which 
the container is intended to carry. 

Second. Tests to determine the suitability of the container for 
specified commodities under practical conditions. Such tests should 
be made upon containers filled with the material to be shipped in 
them or with some other very similar in its action on the container. 

In the case of the first class of tests seepage through the pores and 
the first leak depend largely upon the nature of the lining and of the 
contained liquid. A material difference might be expected in the 
behavior of barrels fined with paraffin and filled with water as com- 
pared with barrels lined with glue and filled with gasoline. In the 
drop test the height of drop also depends upon the specific gravity of 
the contained liquid. The height of drop required to produce given 
stresses is in approximately inverse proportion to the combined weight 
of barrel and contents. • 

Having made tests of the first class, and so determined the best 
construction, it then remains to manufacture containers in accordance 
with specifications based upon the results of these tests. Tests of 
the second class made upon such containers lined according to com- 
mercial practice and filled with the commodity they are to carry 
would show their limitations under practical conditions. 

In the case of barrels internal-pressure and side-drop tests are 
recommended for this purpose. 



BULLETIN 86, U. S. DEPARTMENT OF AGRICULTURE. 



Table 3. — Individual tests — Side compression. 
§-rNCH BARRELS. 



No. 


Num- 


Deflec- 
tion. 




Rate 




of 


ber of 


Load. 


of 


Remarks. 


barrel. 


hoops. 




leaking. 












Lis. per 












minute. 




1 


6 


0.S1 


5,000 




Seepage through pores. 






1.12 


6,000 




Staves slip. 






1.24 
2.35 
3.80 


6,340 
8,920 
11,000 




Leak between staves. 

Stave broke. 

Horizontal shear in top stave. 




1.6 






5.38 


14,380 


6.5 


Stave broke. 






6.35 


13,640 


42.8 


One-half contents escaped. 


2 


6 


.88 
1.20 
2.54 


5,000 
6,000 
8,500 




Leak at chime. 
Stave slipped. 
Stave sheared. 




1.7 






5.97 


10,850 


29.0 


One-half contents escaped. 


la 


8 


.85 
1.08 


5,500 
6,500 




Leak between staves. 
Staves slip. 








2.80 


9,400 


2.1 


Bottom stave sheared. 






3.80 


11,250 


15.0 


Stave split. 






4.37 


11,000 


23.0 


Stave broke. 






5.40 


12,310 


31.0 


Do. 






5.70 


11,880 


32.0 


One-half contents escaped. 


2a 


8 


.60 


4,500 




Seepage through pores. 






.64 


4,750 
7,500 




Leakage around end at bottom. 








3.80 


12,320 


2.9 


Stave broke. 






4.62 


12,070 


2.0 


Bottom stave broke. 






7.11 


15,040 


28.0 


Stave broke. 






7.61 


15,370 


52.0 


One-half contents escaped. 



a-INCH BARRELS. 



9 
10 

9a 
10a 


6 
6 
8 
8 


0.57 

.77 

.86 

2.35 

3.36 

3.75 

.77 

.90 

1.24 

2.88 

4.00 

4.30 

.64 

.86 

1.15 

3.60 

4.35 

4.53 

.57 

1.03 

1.70 

3.80 


5,000 
6,000 
6,500 
9,730 
10, 830 
11,380 
5,500 
6,000 
7,000 
10,910 
11,110 
10, 420 
5,500 
6,500 
8,000 
11,590 
12, 430 
12, 390 
5,000 
7,000 
8,860 
12,010 




Leak at chime. 
Seepage through pores. 
Staves slip. 
Stave broke. 

Do. 
One-half contents escaped. 
Seepage through pores. 
Staves slip. 

Leak between staves and at chimes. 
Bottom stave broke. 
Increased breaking. 
One-half contents escaped. 
Leak between staves. 
Leak at chime. 
Staves slip. 
Top stave sheared. 
Bottom stave broke. 
One-half contents escaped. 
Leak at chime. 
Staves slip. 
Leak between staves. 
One-half contents escaped. 






10.5 
37.0 

39.4 






9.0 
39.0 

57.0 






25.2 

37.5 
33.6 




1.0 
34.0 











i-INCH 


BARRELS. 


17 

18 
17a 

18a 


6 

6 
8 

8 


0.86 
1.20 
4.27 
4.40 
4.91 
5.58 

.90 
1.10 
1.63 
2.14 
5.78 

.56 

.92 
1.22 
2.75 
3.75 
4.15 
4.65 
4.88 

.83 
1.00 
2.95 
5.43 
5.50 
6.40 


5,500 
6,500 
12, 870 
12,260 
11,110 
11,830 
6,500 
7,000 
8,500 
9,000 
12,940 
4,500 
6,000 
7,000 
10, 750 
12, 150 
12, 200 
12, 530 
13,020 
6,000 
6,500 
11,100 
16,280 
15,190 
14,090 




Leak at chime. 
Staves slip. 
Top stave broke. 

Do. 
Stave broke. 

One-half contents escaped. 
Leak through joint of head. 
Seepage through pores. 
Leak between staves. 
Stave broke. 

One-half contents escaped. 
Leak at chime. 
Seepage through pores. 
Staves slip. 
Head coming loose. 
Top stave broke. 

Do. 
Stave broke. 

One-half contents escaped. 
Leak at chime; staves slip. 
Leak between staves. 
Top stave broke. 
Bottom stave broke. 

Do. 
One-half contents escaped. 




21.3 
24.8 
28.0 
36.2 






1.5 
26.8 






5.1 
23.1 
35.4 
34.0 
40.0 




1.0 
20.0 
20.0 
40.5 



TESTS OF WOODEN BARRELS. 



Table 4. — Individual tests— Diagonal compression. 
f-INCH BARRELS. 



No. 

of 

barrel. 


Num- 
ber of 
hoops. 


Deflec- 
tion. 


Load. 


Rate 

of 

leaking. 


Remarks. 


3 

4 
3a 

4a 


6 

6 
8 

8 


0.56 
1.45 
3.40 
3.56 

.77 
3.78 
4.48 

.85 
1.38 
1.55 
2.26 
2.85 

.97 
1.73 
2.50 


7,000 
11,000 
15, 620 
10, 020 

8,000 
16,240 
16, 990 

8,500 
13,000 
14,000 
16,400 
15,000 

8,500 
14, 480 
15,440 


Lbs. per 
minute. 


Leak at chime. 

Staves sheared. 

Bottom head broke. 

One-half contents escaped. 

Leak at chime; staves slipping. 

Bottom head broke. 

One-half contents escaped. 

Leak at bottom chime. 

Leak at top chime. 

Staves slipping. 

Top head breaking. 

Top head broke. 

Leaks at top and bottom chimes. 

Staves slip; bottom head breaking. 

Bottom head broke. 


1.0 

6.0 




13.5 
80.0 






4.5 

7.5 


4.0 
14.5 



f-INCH BARRELS. 



11 

12 

11a 
12a 


6 

6 

8 
8 


0.62 
1.18 
1.50 
5.73 
8.42 

.90 
1.26 
1.50 
3.20 

.58 
1.48 
2.10 

.75 
1.53 
2.47 
9.25 


7,500 
11,000 
12, 460 
17, 000 
17,850 

9,000 
11, 500 
12, 500 
16, 530 

8,000 
14, 500 
16, 000 

8,000 
14,000 
16, 970 
24, 260 




Leak at chime. 

Leak at bearing. 

Top head broke; staves sheared. 

Staves breaking at top. 

One-half contents escaped. 

Leak at bottom stave. 

Stave splitting at top. 

Leak at bottom chime. 

Bottom head broke. 

Leak at bottom chime. 

Staves slipping. 

Top head broke. 

Leak at top chime. 

Staves slipping. 

Top head broke. 

Test discontinued. 






0.5 
39.0 






8.8 


2.5 

6.0 




4.7 
16.0 



J-INCH BARRELS. 



19 

20 

19a 

20a 

1 


6 

6 

8 
8 


0.42 

.77 

1.68 

3.73 

5.50 

7.47 

.81 

1.12 

2.34 

4.20 

5.00 

.62 

1.43 

3.83 

4.85 

5.05 

.82 

.95 

1.27 

2.35 

2.70 


6,500 
8,500 
11,500 
17, 660 
18, 000 
11, 540 
9,500 

10, 500 
14, 5G0 

19, 280 

20, 530 
8,000 

13, 000 
19, 790 
21, 740 

21, 650 
11,000 

11, 500 
12, 500 
16, 500 
17,200 




Leak at bottom chime. 

Staves slipping. 

Leak at top chime. 

Top head splitting. 

Top head broke. 

One-half contents escaped. 

Leak at bottom chime; staves slipping. 

Leak between staves at bottom. 

Staves slipping. 

Top head breaking. 

Top head broke. 

Leak at bottom chime. 

Staves slipping. 

Staves sheared at chime. 

Top head broke. 

One-half contents escaped. 

Leak at bottom chime. 

Staves slipping. 

Leak at top chime. 

Bottom head breaking. 

Bottom head broke. 






4.0 

32.0 

9.3 






7.2 
21.0 




11.0 
36.6 
72.0 













10 



BULLETIN 86, U. S. DEPARTMENT OF AGRICULTURE. 



Table 5. — Individual tests — Drop tests. 
f-LNCH BARRELS. 



No. of 
barrel. 



Num- 
ber of 
boops. 



Height 
of drop, 



Rate of 
leakage. 



Remarks. 



SIDE DROP. 



6 
8 


Inches. 

6 

12 

18 

24 

30 



9 

12 

24 

27 


Lbs. per 
minute. 




0.3 
2!o 






.3 

2.0 



Stave slipped; leak at chimes. 

Leak between staves. 

Stave cracked. 

Head cracked; hoops slipped at head. 

Head broke out. 

Leak at chime and between staves. 

Staves slipping. 

Stave broke. 

Flag coming out at head. 

Head broke out; split at dowels. 



DIAGONAL DROP. 



Leak at chime. 
Head broke. 
Head broke out. 



1-INCH BARRELS. 



SIDE DROP. 


13 

13a 


6 

8 



9 
15 
24 
39 
9 
12 
21 




Leaking slightly. 

Leak of chime and between staves. 

Stave broke. 

Hoop slipped at head. 

Test discontinued. 

Leak at chime; stave slipped. 

Stave broke. 

Bilge hoop slipped. 




0.2 

1.0 

23.2 




35.7 


DIAGONAL DROP. 


14 

14a 


6 
8 


9 
15 
18 

9 
15 
18 




Leak at chime. 
Head failing. 
Head broke out. 
Leak between staves. 
Flag coming out. 
Head broke out. 










0.3 



2-INCH BARRELS. 



SIDE DROP. 


21 

21a 


6 
8 


9 
21 
24 
27 
48 

9 
21 
33 
36 




Leaks at chimes; staves slipped. 

Stave broke. 

Bilge hoop slips. 

Head hoop slipped. 

Test discontinued. 

Stave slips. 

Leak at chime. 

Head broke. 

Head broke out. 






2.0 
11.3 




.3 

.7 


DIAGONAL DROP. 


22 
22a 


6 
8 


6 
12 
15 
21 
15 
is 




Leak at chime. 

Stave sheared. 

Leak through joint of head. 

Head broke out. 

Head breaking. 

Head broke out. 




0.7 
.3 
.6 
.4 



TESTS OF WOODEN BARRELS. 



II 



Table 6. — Individual tests — Internal pressure. 
f-INCH BARRELS. 



No. of 
barrel. 


Num- 
ber of 
hoops. 


Pres- 
sure. 


Rate of leakage. 


Remarks. 


7 
8 

7a 
8a 


6 

6 

8 
8 


Lbs. per 
sq. inch. 
2 
4 
8 
10 
12 
2 
4 
6 
8 
10 
12 
13 
4 
8 

10 
16 
2 
4 
8 

12 
14 


Drops per 
minute. 


Lbs. per 

minute. 


Seepage through pores. 
Leak between staves. 
Head bulged flush with chime. 
Leak at chime; broken stream. 
Leak between staves. 
Leak at chime. 

Leak between staves at bilge. 

Heads bulged flush with chimes. 

Seeping in stream through pores. 

Leak through joints of head. 

Displacement of flag. 

Seepage through pores. 

Leak at chimes and head bulged flush with 

chime. 
Leak through joints at end. 
Flag forced out. 
Seepage through pores. 
Leak between staves at end. 
Head bulged flush with chime; leak between 

staves at bilge and through joints in head. 

Leak in head. 


5 
120 










4 




200 






























120 


















60 




1.2 





f-INCH BARRELS. 



15 
16 

15a 
16a 


6 
6 

8 

8 


2 

6 

8 

12 

14 

16 

2 

4 

10 

14 

16 

18 

22 

2 

4 

10 

12 

14 

18 

2 

4 

8 

10 

14 

16 

22 

24 






Seepage through pores. 
Leak between staves at end. 
Streaming between staves at end. 

Head bulged flush with chime. 
Leak between staves at bilge. 
Seepage through pores; leak at chime. 

Leak between staves at bilge. 
Heads bulged flush with chime. 
Leak between staves at quarter. 
General leak between staves. 
Seepage through pores. 
Leak at chime. 
Squirting at chime. 
Leak between staves at end. 
Head bulged flush with chime. 
Test discontinued. 
Seepage through pores. 
Leak at chime. 

Leak between staves at bilge. 

Head bulged flush with chime. 

Stream through joints of head. 

Leak through joints of head; displaced flag. 






108 
120 










2.0 




26 

96 








132 








2.0 




60 
















2.4 








2 

20 








38 















i-INCH BARRELS. 



23 
24 


6 
6 


4 

8 
12 
14 
18 
20 
24 

4 
10 
12 
14 
18 
20 
28 






Leak at chime and at flag; seepage through 
pores. 

Leak between staves at bilge. 

Head bulged flush with chime. 

Leak at joint of head. 

Leak between staves. 

Seepage through pores; leak at chime. 

Leak between staves at quarter. 
Leak between staves at bilge. 
Head bulged flush with chime. 
Leak at joints of head. 
Leak between staves. 


6 

14 


















1.2 




52 

50 








70 

82 






1.5 





12 



BULLETIN 86, U. S. DEPARTMENT OF AGRICULTURE. 



Table 6. — Individual tests — Internal pressure — Continued. 
i-INCH BARRELS— Continued. 



No. of 
barrel. 


Num- 
ber of 
hoops. 


Pres- 
sure. 


Rate of leakage. 


Remarks. 


23a 
24a 


8 
8 


Lbs. per 
sq. inch. 
6 
12 
16 
20 
30 
4 
8 
16 
18 
22 
24 

30 
36 
38 


Drops per 
minute. 


Lbs. per 
minute. 


Seepage through pores; leak at joints of head. 

Head bulged flush with chime. 
Leak between staves at bilge. 
Test discontinued. 
Leak between staves at chime. 
Seepage through pores. 

Leak between staves at quarter. 
Head bulged flush with chime. 
I^eak at joints of head; leak between staves at 
bilge. 

Head breaking. 
Head broke out. 


20 

84 
180 








2.0 








4 
12 












36 















Table 7. — Individual tests — Made-up barrels. 

INTERNAL-PRESSURE TESTS. 



No. of 
barrel. 


Num- 
ber of 
hoops. 


Pres- 
sure. 


Rate of leakage. 


Remarks. 




8 
8 


Lbs. per 

sq. in. 

4 

10 

14 

16 

22 

26 

32 

34 

4 

6 

12 

18 

24 

26 to 36 

38 


Drops per 
minute. 


Lbs. per 
minute. 


Leak through defective joint in head. 
Leak at defective joint ceasing. 
Head bulged flush with chime. 

Head split at joint. 
Seepage through pores. 
Leak at chime. 

Head bulged flush with chime. 
Leaking in broken stream. 
Head forced out. 


115 






55 
56 
55 
130 
















6 
130 

180 























DROP TESTS. 



No. of 
barrel. 


Num- 
ber of 
hoops. 


Height 
of drop. 


Rate of 
leakage. 


Remarks. 


SIDE DROP. 




8 


Inches. 
12 
18 
21 
33 


Lbs. per 
minute. 


Leak at chime; stave slips. 

Stave cracked. 

Hoop slips. 

Two broken staves. 






21.0 


DIAGONAL DROP. 




8 


9 
12 
IS 
21 




Leak at chime. 
Stave slips. 
Head failing. 
Head broke out. 






7.7 




BULLETIN OF THE 



No. 87 



Contribution from the Forest Service, Henry S. Graves, Forester 
June 4, 1914. 




FLUMES AND FLUMING. 1 

By Eugene S. Bruce, Expert Lumberman. 

INCREASING IMPORTANCE OF FLUMES. 

The growing scarcity of accessible areas of virgin forests from 
which timber can be transported cheaply by streams to central 
points for manufacture has called into being additional systems of 
handling and transporting logs and timber, as exemplified in the 
different forms of railroad logging, and in such adjunctive features of 
logging as donkey engines, overhead cableway skidders, flumes, etc. 

Repeated inquiries for information regarding flumes and flume 
construction are responsible for the present discussion. This method 
of transportation may be classed as an amplification of log driving, 
through using water as the transporting medium, but in a much 
smaller quantity and in a more closely confined and controlled form 
through the aid of artificial and smoother "banks," as represented 
by the sides of the flume. It also gives to the operator the additional 
advantage of being able to direct the transporting agency, under 
certain fixed limitations, to a desired point sometimes far away from 
any natural stream of water. 

The use of flumes for transporting timber or lumber from localities 
which at the present time are commercially unprofitable to log will 
undoubtedly increase in the future. There are large areas of pri- 
vately owned timber in the higher elevations of the mountainous 
regions which could be taken out if the cost of logging could be 
brought low enough to insure a reasonable profit to the operator, 
and there are a great many localities in the National Forests, which 
in most cases include the tops of the mountain ranges, where the 
construction and use of certain types of flumes using the minimum 
amount of water will make it possible to remove the timber or lum- 
ber with the aid of - the small streams having their rise in the 
mountains. 

1 Discusses the use of flumes in lumbering operations and tells how to build them. Of especial value to 
lumbermen and log drivers. 

33346°— 14 1 



2 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

This increased usage will simply be the logical result of conditions. 
The removal of timber by flumes from many localities is to-day the 
only economical method. There are a great many localities where 
timber is at present being taken out at a loss, but where, if an up-to- 
date flume had been built at the inception of the lumbering opera- 
tion, instead of starting with the methods at present used, much 
more satisfactory results would have been shown. 

FORMS OF LUMBER TRANSPORTED BY FLUMES. 

The different forms in which lumber or timber is generally trans- 
ported by flumes at the present time are as follows : 

(1) In logs. 

(2) In piling, mining ' 'stulls," or long timbers. 

(3) In railroad crossties. 

(4) In "cants" or split-log form. 

(5) In lumber "loose" boards or planks. 

(6) In lumber "brailed" or clamped together. 

(7) In cordwood or pulpwood. 

There is hardly any limit to the forms in which lumber may be 
transported in flumes, provided it is of a species that will float and 
the flume is constructed with due regard for the material to be handled. 
The logging conditions, species and character of material to be 
handled, amount of water available for fluming purposes, etc., all 
have a very direct bearing on the form of flume and the methods 
used in construction. Thus, in a locality where the supply of water 
is ample and there is no necessity for husbanding it, a type of flume 
might be used which in another locality where there was a scarcity or 
lack of water might be very undesirable. 

The very important feature of water supply has, in fact, had much 
to do in determining the type of flume that is being used in different 
localities; since where water is plentiful and there is no particular 
need of being economical in its use, a square or box-like flume of almost 
any size will do for either logs or lumber, while in other localities it 
has been found absolutely necessary, on account of the small volume 
of water available or for other reasons, to use a type of flume which, 
with approximately one-half the volume of water necessary in the 
square or box type of flume, will handle practically the same class of 
material. Thus it is quite common in the Appalachian Mountain 
region to see box or square sided flumes in use, while in the moun- 
tainous western portions of the United States the square-box flume 
is rarely seen, and the V-shaped flume is the one in general use. 
Necessity, therefore, has in the past and undoubtedly will in the 
future be the principal factor in deciding what type of flume shall be 
constructed. 



FLUMES AND FLUMING. 3 

TYPES OF FLUMES. 

There are only two types of flumes in general use in the United 
States at the present time — 

(1) The box or square upright-sided flume. 

(2) The V-shaped flume. 

The square flume is usually constructed along the general lines of 
the well-known mill flume or artificial conduit used to convey water 
from the mill pond to the mill for water power or other purposes, but 
with this difference, that the uprights on the sides of the square or 
box timber flume are rarely braced across the top of the flume, but 
instead the top of the flume is left open to afford free passage for logs, 
wood, or lumber, and the sides are held in place by uprights fastened 
on the sills or crosspieces on which the bottom of the flume rests, and 
braced from the outside. (See fig. 1.) 

This is the oldest type of wooden flume in use, and is employed to 
some extent at the present time where economy in the use of water is 
not of any particular importance. However, the square flume requires 
more water to operate successfully with the same class of material, 
and, generally speaking, requires more lumber for construction than 
does the V-shaped flume. Furthermore, the material being handled 
is more apt to "jam" (especially the short material) in the square- 
box type. Owing to the form of its construction there are more 
joints in this type that are liable to open up and cause "leakage," in 
case the flume is allowed to stand without water running in it for any 
length of time, and except where it is desired to combine in one flume 
the two objects of carrying a large amount of water to be used for 
some purpose other than fluming below and at the same time to use 
the flume for the transportation of lumber or timber, it is generally 
more advisable to use the type of flume which requires the least 
amount of water and the least average amount of repair. Up to the 
present that is the V-shaped wooden flume, but it is perhaps not a 
flight of fancy to predict that it is only a question of time when 
strong and light " sectional" metal flumes, semicircular in form, that 
can be quickly taken apart and transported from one point to another 
and put together and set up again, will be in common use. Metal 
semicircular conduits, made in sections and easily put together, have 
already been used in hydroelectric and irrigation projects. 

There is a conduit of this character in operation on the Sierra Na- 
tional Forest in California, and the writer sees no reason why a similar 
type of metal conduit, lighter in construction and somewhat modified 
in form, could not be developed for log or lumber flumes. The initial 
cost of construction would, of course, be considerably greater than for 
a wooden flume, but the metal one would have much greater dura- 
bility and length of service. 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 




FLUMES AND FLUMIKG. 



THE WOODEN V-SHAPE FLUME. 



The V-shaped flume is at present the type of flume most generally 
used in the western portion of the United States, and it has given the 
most general satisfaction for the transportation of manufactured 
lumber or timber in its different forms of logs, railroad crossties, 
cordwood, etc. Some of these flumes have been in successful opera- 
tion for a number of years, and the writer, who has personally exam- 
ined many of them, has no hesitancy in saying that, if he were to con- 
struct a flume, the V-shaped flume is the type he would erect. 

Some of the salient points in which the V-shaped flume excels 
are: 

(1) It can be successfully operated with a less volume of water 
than any other type, since, owing to the V form of construction, 
the water is always held confined or "compact," and therefore has 
the greatest carrying power for the amount used. 

(2) There is less likelihood of jams forming, since the narrowness 
of the flume prevents the material from getting partially crosswise 
and forming a "brace" through the ends, "wedging" or pressing 
against the sides of the flume. This is a feature especially desirable 
when handling short material. The narrow formation of the V- 
shaped flume keeps the timber running "straight," and according 
as the volume of water in the flume is reduced the formation of the 
V keeps the water confined in the smallest possible triangle down 
which the sides of the flume compel the material to travel. 

(3) In fluming logs or round timbers the rounded portion of the 
log settles well down into the V. The water thus confined between 
the bottom of the stick and the sides of the V constantly tends to 
lift the log, and this keeps the stick from settling down or rubbing 
hard against the sides of the flume. In a square flume, on the other 
hand, the same amount of water could run on both sides of the log 
and not beneath and would so lose the tendency to "lift" through 
lack of proper confinement. 

Thus if a log or stick of timber is large and heavy, it may some- 
times nearly fill the V-shaped flume and occasionally touch both 
sides. But whenever this occurs the log has the pressure of the full 
volume of water which the flume can carry backed up behind it 
to force it along, and the V formation keeps the stick running 
"straight ahead," so that there is very little opportunity for the 
water to spread out or run around or get by the stick without taking 
it along with it. Its transportation is further aided by the uplift 
of the partially confined water, running around and under it, that 
is trying to find an outlet or relief from the pressure of the water 
behind, which must either aid in forcing the stick along or run over 
the top of the flume. 



6 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

(4) In cases where it is necessary to have an unusually abrupt 
descent in some portions of the grade, the V-shaped flume is best 
adapted to serve as a "slide" or "slip," or "chute," since it is less 
likel} r to become jammed, while the material being handled is held 
by its own weight in proper position in the center of the V. In a 
great many localities this particular feature of control of the log 
or stick of timber when it is "coasting" will be found very neces- 
sary in handling material from the higher mountain slopes, espe- 
cially in places where it is impossible to maintain a steady and 
equable grade from the top to the bottom of the mountain without 
too great expense, and where it may be necessary to have a form 
oi construction that will carry logs or timber safely for a long dis- 
tance when the grade is so abrupt that it is impossible to maintain a 
sufficient volume of water in the flume to prevent the material from 
rubbing or sliding along on the sides and bottom. In such localities 
and under such conditions the V-shaped flume, when strongly con- 
structed so as to combine both the objects of flume and chute, has 
been and will be found altogether the most desirable. 

DEGREE OP ANGLE FOR "V "-SHAPED FLUME BOXES. 

In the construction of the sections or "boxes" in V-shaped flumes 
a number of different degrees of angles have been used in the past. 
In some instances the constructors have used an angle as low as 70 
degrees, while others have constructed flumes with an angle of 110 
degrees. The results of experience and the consensus of opinion, 
however, are that the 90-degree or straight right angle is the most 
satisfactory form of V-box construction for all purposes, and this is 
the degree of angle that is referred to when speaking of V-shaped 
flumes in this bulletin unless otherwise specifically stated. 

METHODS OP CONSTRUCTING THE "v "-SHAPED PLUME. 

There are many different methods and styles of construction used 
in building V-shaped flumes, varying according to the kind of material 
to be handled. In some cases the brackets or frames that support 
the sides of the V are made from round pole wood simply flattened 
on one side so as to give an even surfaced support to the boards 
forming the "lining" or inside of the V, while the sills, stringers, 
braces, and trestling may be constructed from small round timber 
or poles, leaving only the lining or inside of the box to be constructed 
from sawed lumber. The form of construction of the different sec- 
tions of the flume, or, as they are called, "boxes," also varies in length 
from short ones of 6 feet up to those of 20 feet. In the con- 
struction of the lining or inside of the boxes, lumber of variable 
thickness and width is used. The boxes are sometimes made of only 
one thickness of boards simply joined together, but more commonly 



FLUMES AND FLUMING. 7 

the lining of boxes is constructed with two thicknesses of boards 
with the joints broken by varying the width of the boards, as shown 
in figure 2. Another form of box construction is by the use of a 
single thickness of boards with "battens" to cover the joints, the 
battens being spiked over the joints on the outside in the sections 
between the brackets or arms, as shown in figure 3. There is still 
another form of box construction in which the battens are continuous. 
(See fig. 4.) In such cases the battens are "cut in" or set into the 
arms or brackets on the outside of the V, thus making a continuous 
"broken joint." 

There are certain individual advantages in each of these different 
styles of box construction, and the right one to use is a question 
which the prospective operator must always determine for himself. 
The use of the continuous battening running under the arms requires 
some cutting into the bracket frames or arms in order to let the 
battens pass through them, and consequently, to a certain extent, 
weakens the arms. This usually necessitates a heavier arm than 
would be required if the battens only reached from one arm to 
another and were spiked over the joint entirely independent of the 
"arm." On the other hand, the continuous battens are held firmly 
in place by the arms and braces, and it is almost impossible for bat- 
tens properly put on in this manner to get out of place while the 
arms and braces are firmly in position. 

The use of the double-lined box with joints broken is contended 
for by some operators on the ground that it is always necessary to 
replace the fining of the boxes occasionally on curves and in places 
where the passage of lumber wears most rapidly. It is also con- 
tended that the doubled box retains moisture much better between 
the two linings and, therefore, will permit of the flume standing idle 
without any water rumiing in it, for repairs or other reasons, for a 
much longer period of time without the boxes becoming thoroughly 
dried out and "checking" so that the flume will leak, or warping out 
of shape and position, or drawing the nails used to hold the lining in 
place. The battening between the different arms or frames makes 
it possible to use almost any width or thickness of material for this 
purpose. It can be put on or taken off without interfering with any 
of the other forms of construction, and this feature also has its 
ardent supporters. 

TRIANGULAR BLOCKS IN THE BOTTOM OF THE ""V." 

In some instances it has been thought advisable to fill the bottom 
of the V in a flume with a triangular section of wood sawed in such 
form that it would fit snugly into the bottom of the V on the inside. 
Some constructors claim that this block serves the twofold purpose of 
reducing the amount of water necessary in operating a flume and 



s 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



also strengthens the flume itself. It is not believed, however, that 
the benefit to be derived from this form of construction is sufficient 
to compensate for the increased cost of construction and the greater 



3" X 6" Arm, 
2.' 5" Long 



3"* 6" Brace. 
/3 "Long 



4"x6"fbsf Batter.. 




- 
Fig. 2.— End view of V-shaped flume, showing method of construction and double-lined box.- 

amount of material necessary. The prospective constructor should 
be governed by the location, kind of material available for con- 
struction, duration of life of flume desired, and material to be han- 
dled in deciding what type of construction he will adopt. 



FLUMES AND FLTJMING. 




33346°— 14- 



10 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 




PLUMES AND FLUMING. 11 



SIZE OF FLUME. 



The kind of material to be handled is a prime factor in determining 
the size of a flume. If a 30-inch V-shaped flume would satisfactorily 
handle the material, there would be nothing gained by going to the 
extra expense of constructing a flume with a V of 48 inches. On the 
other hand, it is always good policy to construct a flume large enough 
to carry sufficient water to handle the material desired with certainty 
and dispatch. For railroad crossties, cants, poles, cordwood, etc., 
the 30-inch flume is usually large enough, wherever there is a suffi- 
cient volume of water available to fill the flume two-thirds full, while 
for the handling of logs, piling, long timbers, or "brailed" sawed 
lumber it is usually advisable to have the flume constructed with 
the sides of the V from 40 to 60 inches in height, according to the 
volume of water available and the size of the material to be handled. 
This is also a feature in flume construction in which the prospective 
operator can save money by not constructing his flume larger or in 
any more expensive form than is actually needed, since every addi- 
tional inch in height means the use of more lumber in construction, 
and is consequently an added and unnecessary cost. 



METHODS OF CONSTRUCTION. 



For the benefit of those who are entirely unfamiliar with flume 
construction, a description of some of the salient points may be of 
interest. It is usually advisable to erect a small sawmill at or near 
the upper end of a flume location to saw out the lumber needed for 
construction. This material can be floated down the flume as fast 
as the latter is constructed to be used for further extension until the 
whole flume is finally built. This obviates the necessity of hauling 
the construction material, so far as lumber or timber is concerned, 
up grade from the nearest point at which it can be secured, and 
oftentimes cuts out long-distance transportation charges and gen- 
erally reduces the cost of construction, although it usually necessi- 
tates the construction of a passable road for the purpose of hauling 
the necessary boiler, engine, and sawmill machinery to the upper 
end of the flume or place where the construction lumber is to be 
manufactured. 

It will be apparent that the nearer this lumber manufacturing 
point is to the upper end of the flume the more economical will be 
the construction, as it is much cheaper to float the lumber down the 
flume to the place where it is to be used in construction than to haul 
it up grade by teams. Since the flume can usually be filled with 
water as fast as constructed, v/here battens are used, there is no 
great benefit derived from using seasoned lumber for construction 
purposes, although when a flume is constructed of seasoned lumber 
the introduction of the water causes the joints to swell and become 



12 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

tighter than where unseasoned lumber is used. The power used for 
operating the small mill to cut out the necessary timber and lumber 
to construct a flume is usually the ordinary portable type of boiler 
and engine, sometimes in the combined form. There will be found 
cases and localities in which the use of an overshot or an undershot 
water wheel will more economically furnish the necessary power, 
where there is an ample supply of water and favorable conditions for 
Hs being used for this purpose, and there will be some cases in which 
electric power to operate the mill, transmitted from a convenient 
line of some electric-power plant, will be found most economical. 

After the mill is installed it is advisable to use prepared frames, 
"forms," or miter boxes in cutting the brackets, frames, or arms 
with the "power saw" into the desired length and shape, and also 
in cutting the braces, stringers, sills, overlays, and material for use 
in trestling. Experience has demonstrated that the material can 
be shaped at the mill and transported to the place where it is to be 
used by means of the water in the flume much more economically 
than in any other manner. It is advisable to prepare the frames 
and arms at the mill ready for setting up, and flume them in their 
finished form down to the point where they are to be used; this 
method requiring only that they be placed and fastened in position 
after arriving there. (Fig. 5.) 

A CAREFUL SURVEY NECESSARY. 

An accurate and careful survey of the proposed line of flume con- 
struction is a prime necessity and often a great economy. A need- 
lessly expensive survey should always be avoided, but accuracy of 
grade and careful and reliable "leveling" is imperative in order to 
insure lasting flume construction. The equalization of grade is very 
advisable wherever it can be accomplished without too great an 
expense. And right here a practical knowledge of the comparative 
benefits to be derived from having a steady or an even and moderate 
grade, considered in relation to cost, is of great value. The grading 
of soil in knolls or hillocks or ridges along the prospective flume line 
is advisable up to a certain point, if necessary to maintain a reason- 
ably steady grade for the flume. A careful preliminary survey fol- 
lowed by a location survey, using a transit and level, will make it 
possible to obtain a reliably constructed profile map which will show 
to the prospective operator what the grading should be at different 
points of his line. It is always best to know just what the grade 
is going to be when completed, and approximately what it is 
going to cost, before starting the construction work. No detailed 
estimate of the cost of survey is included here, for the reason that 
the wide range in conditions where flumes might be constructed 
would make any set figures unreliable and possibly misleading. A 



FLUMES AND FLUMING, 



13 




S.V <D 



14 BULLETIN" 87, U. S. DEPARTMENT OF AGRICULTURE. 

reliable survey, however, is absolutely necessary, and a carefully 
constructed profile map highly desirable before construction begins. 
The cost of the completed survey would be comparable to that of a 
branch railway location. 

The blasting out of rocks and bowlders or projecting points of 
bluffs is sometimes advisable and necessary in order to reduce curva- 
ture and allow the flume to run in as direct a line as possible. This 
reduces the danger of "jamming" and makes it possible to handle 
longer material without its "binding" as a result of the ends "press- 
ing" against the lining of the flume on the outside of the curve 
while the middle of the stick presses against the lining on the inside. 
Just what is necessary to be done in this respect can best be calculated 
by using a carefully prepared profile map made from an actual sur- 
vey of the proposed flume line. 



The matter of grade in flume construction is one of great impor- 
tance. It is not always possible to vary the location so as to maintain 
an equable or steady, even grade in all portions of a flume line, but 
wherever it can be accomplished without incurring too great an 
expense it should always be done. Flume operators have found 
the question of satisfactory grade to be one of the most important 
features of successfully fluming material, since where there is a 
stretch of comparatively flat grade the supply of water may be 
ample to nearly fill the flume, but upon arrival at a point in the 
flume fine where the descent is very abrupt, the accelerated speed 
of the water reduces its volume to a small amount in the bottom 
of the flume and, consequently, results in the flumed material "rub- 
bing" or "sliding" down the descent for a long distance on the sides 
of the V. Such action wears out the lining very rapidly, necessitates 
its being frequently renewed, and produces a dangerous condition 
through the liability of the material to jam and pile up, and either 
be thrown out of the flume or break it down as a result of the in- 
creased weight. 

In general, the lowest grade that is considered satisfactory for 
successful operation is approximately 1 per cent, or 1 foot in 100 
feet, but it is better to maintain a grade of from 2 to 5 per cent 
when possible. The maximum grade that can be used runs up 
to a very high pitch; some flumes have been successfully operated 
for a short distance at a grade of 30°, but such a steep grade is 
very undesirable, as it is usually impossible to maintian a sufficient 
volume of water in the flume. The most satisfactory results in flum- 
ing will be obtained at from 2 to 10 per cent grade, and it should be 
held below 15 per cent whenever possible. 



FLUMES AND FLUMIZSTG. 15 



TRESTLING. 



In maintaining the steady or even grade of a flume it is nearly 
always necessary to do more or less "trestling," in order to avoid 
mievenness in the line, reduce distance and abrupt curvature, and 
hold the general grade of the flume at the desired height. (PL I.) 
Here, again, the necessity of a careful survey becomes apparent, for 
without a knowledge of just what the height of the trestling needs 
to be in each successive 12 to 16 foot distance, it would be impossible 
to know just what length the bents and braces of the trestling should 
be cut, or just what "pitch" should be given to the bracing legs of the 
trestle, or just where the foundation "stepping" should be placed 
in order to hold the top of the flume firmly in the desired position. 

I can not make the question of the necessity of a careful survey 
too important, especially for a mountainous or rough and rugged 
country, which is the type of locality in which considerable trestling 
is most likely to be used. In this connection, it is sometimes very 
advisable in the interest of economy, and necessary from the view- 
point of successful operation, to grade out the earth along the sides 
of ridges, where this can be done cheaper than trestling can be con- 
structed in other localities along the line, for its effect in maintaining 
the desired grade. Also, grading out is in some cases desirable in 
order that the top of the flume, when completed, may be practically 
on a level or a little below the earth's surface, at least on one side, 
so that logs or heavy timber to be shipped may be "loaded" into the 
flume without having to use a needless amount of energy to get them 
there. 

In many cases the amount of money spent in loading he?~ 
terial into a flume set up unnecessarily high above the earth's sur- 
face has eventually cost the operator much more than it would to havp* 
lowered his flume by grading or slightly changing its course in the 
first place. This is a feature that should not be overlooked. 



In the location of a flume line it is advisable to avoid abrupt curva- 
ture as much as possible. Where the contour of the country makes 
curves or bends in a flume necessary, they should, whenever possible, 
be on long, even lines. (See PI. II.) A sharp curve in a flume 
throws the weight of the material and the water by centrifugal force 
to the outside of the curve, and the abrupt bend in the flume has a 
tendency to dam up or hold back the water. The material is thus 
much more liable to jam or block on an abrupt curve than on a grad- 
ual one. When a jam occurs in the flume the blocked material acts 
as a dam, and after several sticks or pieces of lumber have stopped, 
the front end of the block or jam rests solidly on the sides and bot- 



16 BULLETIN 87, U. S. DEPARTMENT OP AGRICULTURE. 

torn of the flume. In consequence the water is forced over the sides, 
and usually throws the material out of the flume, especially if the 
curve is on an abrupt descent, or else the constantly increasing 
weight of the jam breaks the legs of the trestle, if there be one at this 
point, or perhaps causes the whole framework to collapse. It is then 
often a matter of considerable loss of time and expense before the 
flume is repaired and again ready for operation. The degree of 
curvature should be kept as low as practicable, and should rarely 
be permitted to exceed 20°. 

The length of material to be transported is an important factor in 
deciding the degree of curve that can be used, since very long material 
can not be successfully transported in a flume having a very abrupt 
curve. The curve would have to be sufficiently open to allow the 
chord of curve to be represented by the length of the longest material 
desired to be handled, with a small allowance for clearance. No 
curves should be used in construction that will cause the material 
to "bind." The longer the material the less abrupt curvature is 
permissible, and vice versa. The bracing of a flume on the outside 
of the curve necessarily should be more rigid and stronger than on 
the inside, since the greater pressure " thrust" or "throw" of the 
water and material being shipped is toward the outside of the curve. 
Very abrupt curves require increased bracing and the placing of the 
arms and brackets at shorter intervals, in order to hold the flume 
in its proper position. 

Shorter ' ' boxes ' ' and closer spacing of ' ' bents, " " arms, ' ' and ' - braces ' ' 
on curves. — Where the topographic conditions in a locality are such 
that it becomes absolutely necessary to have abrupt curves in a 
flume, it is advisable to reduce the length of the boxes and correspond- 
ingly shorten the distance that the "bents," "arms," and "braces" 
are placed apart, for the twofold purpose of evening up or reducing 
the sharpness of the angles in the joining of the boxes on the curve, 
and also to give more stability and strength to the flume at the points 
where there will be the greatest strain upon it. It will be apparent 
that long boxes in a flume at a point where there was an abrupt 
degree of curvature would necessitate sharper changes in direction 
than would shorter boxes, thus producing something in the nature 
of square corners. These corners, particularly if there were a rapid 
descent in the flume line at such curve, would have an effect some- 
thing in the nature of a dam or stoppage in the flume, and as a result 
cause the water to slop over or run out over the sides. In addition, 
all material coming down the flume, as a result of the quick change 
in the direction of its course, would "strike" sharply against the 
outside "comer," and the continual pounding of the material against 
the side of the flume would be very likely to jar and eventually 
loosen up the joints at this point, throw the flume out of alignment, 



Bui. 87, U. S Dept. of Agriculture. 



Plate I. 




ll. 87, U. S Dept of Agrici 



Plate II. 




An Unavoidable, Abrupt Curve. 

When material is thrown from a Hume at such a point as this it is practically a loss, 
the men raising the sides of the "V." Trestle is constructed of sawed material. 



Note 



Bui. 87, U. S. Dept. of Agriculture 



Plate III 



i&Hu^Mi Hi 




iiiid$3p*\^k i 




^^^^^ } ^ 


'^H 



Fig. 1.— A Branch Flume, Showing Method of Connection with Main Flume. 
In this case the branch is closed oS by the use of two "lining" blanks. 




Fig. 2.— A Feeder from a Side Creek. 
Notice cheap form of construction. 



Bui. 87, U. S. Dept. of Agriculture. 



Plate IV. 




o "5 



UJ £ 



PLUMES AND FLUMING. 17 

and cause it to leak badly, or at least batter and wear it out more 
rapidly than would be the case if the curve were more gradual. 
More than this, there is always the increased danger of jams or blocks 
occurring in the flume at such points. It is for this reason that shorter 
boxes, which will more evenly graduate the curve, are desirable. 

There are no hard and fast rules that will correctly fit any and all 
conditions, but in general on curves of from 6 to 10 degrees, the boxes 
in a V-shaped flume should be "jointed" at least once in every 12 
feet with corresponding spacing of bents and reinforced bracing. On 
curves exceeding 10° and less than 15° the box should be jointed at 
least once in every 8 feet of length, and on curves of more than 
15° boxes should be jointed at least every 6 feet, with corresponding 
spacing of bents and reinforced bracing in every case. 

As said before, but repeated now for the sake of emphasis, when- 
ever it is possible without incurring too great or prohibitory expense, 
very abrupt curvature should be avoided in flume construction, and 
it will usually be found a wise policy to go to a considerable addi- 
tional expense in excavation work or blasting out of rocks and ledges 
in order to reduce curvature to a satisfactory degree. In every case 
where extreme curvature is unavoidable the foundation footings upon 
which the flume is supported should be carefully placed on very solid 
material, in order to withstand the continued impact and jar of the 
logs striking the sides of the flume; and the entire flume construction 
should be strongly reinforced at such points, not only by shortening 
the length of the boxes and placing the bents, side arms, and braces 
closer together, but also, if trestling is necessary at such points, by 
strongly reinforcing the trestle bracing, both "lateral" and "sway." 

Increase in height of sides of " V" on abrupt curves. — It is advisable 
on abrupt curves to increase or raise the height of the V on the 
outside of the curve, in order to cause the material being shipped to 
drop back into the flume when it tries to "climb," as it always does 
in such places, and thus prevent it getting on top of the side of the 
flume and "riding" until it strikes some little projection or joint and 
forms a "block" or "jam." (See PI. II.) On very sharp curves 
it is usually advisable to raise both sides of the flume a little higher 
than is necessary on tangents and on equable grades, in order to 
retain the water in the flume, especially if there be a very abrupt 
descent at the point of curvature, as is sometimes unavoidably the 
case. The raising of the sides necessitates only the use of a longer 
arm and additional height of the lining of the flume at such points. 

FEEDERS. 

Feeders constructed at various points along a flume line are 
usually necessary in order to maintain the requisite amount of water 
and to furnish a sufficient volume to operate a flume successfully on 

33346°— 14 3 



18 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

the different grades. A volume of water that would be ample to 
handle or float the material satisfactorily on a long stretch of flat 
grade might not be sufficient to furnish an adequate volume to 
prevent the material from rubbing or striking on the bottom in a 
section of the flume where the descent was more rapid; and it is also 
usually necessary to have feeders coming in at different points along 
the line in order to replace the water that has been lost as the result 
of leakage or slopping at the abrupt curves. The side feeders are 
usually brought in from small side creeks by means of a short line 
of V or square flume constructed from a small dam made in a side 
creek at some point where there is sufficient descent to carry the 
water down into the main flume. (See PI. Ill, fig. 2.) The number 
of feeders, the distance apart, and the points where they shall be 
brought in are determined by the necessities of each case. 

Where a main flume fine is following closely the bed of a creek 
having considerable drop, it is usually advisable to take the water 
from the creek itself by means of a feeder flume having a slight down 
grade until it intersects the main flume. This can be done by 
blocking up under the feeder flume, either by trestles or by any other 
economical and convenient form of foundation, until its end will 
reach the top of the V. It is usually advisable to make the feeder 
line as direct as possible and thus avoid increased construction. 
Feeder flumes do not have to be as substantially constructed as the 
main flume lines, since nothing except water is conducted in them, 
nor is the form of construction as important for the same reason. 
Therefore the single-thickness square-box type of flume is often used 
for this purpose. Any method of blocking in under a feeder flume 
that will furnish a substantial foundation is permissible. Here again, 
however, as in the trestling under the main timber or lumber flume, 
too cheap construction, trestling, or blocking is false economy, as the 
work should always be stable enough to be lasting. 

TUNNELING. 

Tunneling through such obstacles as sharp ridges or projecting 
bluffs has sometimes been found advisable, economical, and necessary 
in order to maintain a proper and desirable grade, shorten distance, 
and prevent too abrupt curvature. It is sometimes cheaper to tunnel 
for a short distance through an obstruction than to trestle for a long 
distance in order to raise the line over it or to put in a long curve to 
get around it. It is also sometimes cheaper to tunnel through a ridge 
or projecting point of rocks than it is to make an open cut. This 
has been demonstrated by the practical experience of a number of 
operators. (See PI. IV.) A tunnel should be carefully located by 
survey, so as to be certain that it will be very close to the desired 
grade in order to reduce the amount of necessary excavation to the 



FLUMES AND FLUMLTSTG. 19 

minimum. This will permit of the u stringers" for the flume resting 
on solid foundation in the bottom of the tunnel, which, once solidly 
placed, usually requires little or no repair. 

There is no danger of flumes constructed through tunnels being 
filled as a result of snowstorms nor affected by contraction or warping 
as a result of the sun's rays. The principal danger resulting from 
construction through tunnels is that of material falling into the 
flume from the top of the tunnel, unless it is protected, when the 
tunnel is through loose earth, by framework and lagging over the 
top of the flume. This danger, of course, does not exist where a 
tunnel is driven through solid rock, as the rock itself furnishes a 
stable roofing. And if the earth through which the tunnel is driven 
is solid, it is not always necessary to go to the expense of setting up 
frames and placing "lagging" over the top of the flume, since what 
small amount of loose earth does drop into the flume as a rule will 
quickly be dissolved and washed away by the running water. It is 
usually possible, by varying the flume-fine location, to get around 
obstacles without going to the expense of driving a tunnel through 
rocks and ridges, but there will be found cases in which it is im- 
possible to secure a satisfactory location and at the same time 
maintain a desirable grade and avoid very abrupt curves without 
resorting to tunneling. 

SMALL HOLDING RESERVOIRS AT DIFFERENT POINTS OF FLUME. 

It is sometimes advisable to have small holding reservoirs or 
" catch basins" constructed at different points along a flume line, 
where it can be done without involving prohibitive expense, in order 
to provide an additional storage place for logs, crossties, or rough 
lumber. The upper end of a flume may have to be used to its fullest 
capacity for a short time in the spring, when the melting snow and 
early spring rains will furnish a sufficient volume of water to transport 
material down to the upper end and past more abrupt portions of the 
flume, and sometimes when this rapid shipment is going on, loading 
or storage facilities at the lower end of the flume may become so 
congested that it is impossible to take care of all the material, even 
temporarily, at that end. 

Under such conditions it is sometimes possible to construct at differ- 
ent points along the line of the flume small storage reservoirs, which can 
be cheaply formed by damming up some small stream or using some 
small natural pond favorably located along the line, thus diverting 
the class of material not desired to be handled clear through at once 
into such reservoir, and taking it out and shipping it later with the aid 
of the increased volume of water available at this lower point of the 
flume. The prospective operator must always be his own judge of 
whether this is necessary and desirable, and should properly take into 



20 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

consideration the possibilities of such features being needed when 
locating the general line along winch his flume is to be constructed. 

Where such features are carefully looked up before the final location 
of a flume line is settled and flume construction has begun, it is some- 
times possible slightly to vary the location of the proposed flume fine 
so as to bring it to the desired grade to be successfully operated in 
connection with a cheaply constructed holding reservoir, without in 
any way decreasing the transporting capacity of the flume. It is also 
sometimes advisable to construct a small reservoir or " catch basin" 
at the foot of an unavoidably long and very abrupt grade, so that 
when the material being shipped leaves the flume or slip it will strike 
into a pond of water and thus avoid being split or broomed. Some- 
times the reservoir and its additional feeders will furnish enough water 
to permit the flume line to be carried on an even grade from the point 
of the " catch basin" or small reservoir at the foot of an abrupt 
descent to its destination. In such cases the reservoir and feeders act 
as equalizers of the volume of water in the flume. 

It has been found necessary in some instances to have small storage 
reservoirs, provided with a small gate that could be quickly closed or 
opened, located at different portions of a flume where no feeders were 
available, in order to obtain a sufficient volume of water to carry the 
material being handled to the next station or reservoir, or to its desti- 
nation. Where conditions obtain that make this kind of an operation 
necessary, it is usually advisable to have the mouth of the "intake" 
considerably wider than the flume, which permits the water to go into 
the flume opening in a wide unobstructed flow. 

When operating under such conditions it is always advisable to let 
the water in the flume run for a short time before any material is 
shipped. Otherwise the material receives a strongly accelerated 
movement on the rapid descents, and is therefore carried by its own 
weight and momentum into the slower moving volume of water in the 
flat grades at a greater rate of speed than the water is moving, and 
consequently runs slightly faster than the water. For this reason 
the water should always be allowed to run in the flume for a sufficient 
time to be sure that the latter will be filled its whole length, or at least 
to the next station below, before any material is started on its way 
from the shipping point above. 

RESERVOIR PONDS AT HEAD OF FLUMES. 

It is advisable and oftentimes necessary to make a small artificial 
pond or reservoir at the upper end of a flume in which to "land" or 
"bank" the material to be shipped, especially when handling logs, 
railroad crossties, or heavy unmanufactured material of any kind. 
Conditions sometimes make it possible to use the ice on a pond of this 



FLUMES AND FLUMING. 21 

character at the head of a flume as a banking ground in the winter or 
a place to land and hold the material to be transported by the flume in 
the spring during the time when the cold weather and ice prevent the 
flume's use. 

When a pond is being used for this purpose, if there is more than one 
kind of material being put on the pond, it is usually advisable to place 
substantial booms on the ice between the different classes, so as to 
keep them from getting mixed when the ice in the pond thaws out, and 
further to enable the different classes of material to be shipped accord- 
ing to the desires of the operator or the needs of the manufacturing 
plant, if there be one located at the lower end of the flume. If the 
depth of the pond is sufficient, it is usually more economical to get 
material into a flume from where it is landed on the pond, which 
requires only the separating or "breaking down" of the different piles 
or skidways, than it is to get material into the flume when piled along- 
side. In the latter case some of it will usually be at a distance from 
the flume, thus necessitating either its being loaded onto a dray or 
carried by hand and dumped in. It is much more economical to float 
the material into the flume from a reservoir when this is feasible. 

Probably the most noteworthy example in the United States of 
the construction of a storage dam and flume combined is the Azis- 
cohos Dam, on the Magalloway River in Maine. A particularly in- 
teresting feature of this construction is an "adjustable intake" to 
the V-shaped flume, which is so arranged that it can be quickly 
raised or lowered to suit the varying heights of water in the storage 
reservoir above the dam. The adjustable flume intake has a range 
of 25 feet. This flume, which is a wooden V-shaped one built on 
a large scale, carries the logs from the storage reservoir above the 
dam down past the rapids below the dam on the Magalloway River 
to the still water, where they are released from the flume into the 
river to be floated on down to their destination at the mills on the 
Androscoggin River. Only enough water to bring the river up to 
the required driving "pitch," ha addition to that which passes through 
the flume, is released through the "sluice gates." 

In July, 1913, this flume was handling logs from 12 to 60 feet in 
length at the rate of approximately 1,000,000 board feet in 10 hours, 
with the adjustable intake working satisfactorily at a point 15 feet 
below the maximum water height. The principle of this construc- 
tion is applicable to public or private irrigation projects, or wher- 
ever it is found necessary to take logs or timbers from a high reser- 
voir dam, having greatly varying heights of water at different sea- 
sons of the year, to some more convenient place for manufacture or 
further transportation, using only the minimum amount of water 
necessary to get the material to such point. 



22 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

BRANCH FLUMES. 

Material is sometimes brought to the main flume from side gulches, 
ravines, or small watersheds by the use of what are generally known 
as "branch flumes." (See PL III, fig. 1.) Their use is advisable 
where there is a side valley with a sufficient volume of water availa- 
ble and containing enough material to make the construction of the 
branch flume warranted as being the most economical means of get- 
ting the material to the mam flume. Branch or side-line flumes of 
this character are usually constructed practically the same as the 
main flume, except that it is usually advisable, if a mill has been 
constructed at the upper end of the main flume, to saw the lumber 
at the already constructed mill and flume it down to the most con- 
venient point of the main flume, where it is taken out and from 
there hauled by team to the point at which it is to be used in con- 
structing the branch. Unless the branch were a long one, it would 
hardly justify the erection of a mill for the sole purpose of sawing 
out sufficient lumber to construct it. 

It is sometimes possible to take down a branch flume after the 
material in a gulch, small creek watershed, or ravine has been cleaned 
up, and move it to some other point and again set it up for use. 
Branch flumes are usually brought out and connected up with the 
main flume, as shown in Plate III, figure 1 , so that the material being 
handled will come out into the latter on a gradual curve on the same 
level. Branch-flume lines also act as feeders and serve to maintain 
the volume of water necessary to operate the mam flume. It will 
in some cases be f©und necessary to use the total volume of water 
available from two or more streams in order to have sufficient vol- 
ume to carry the material forward on the lower grades. In such cases 
it is sometimes possible to bring both the material and water together 
at the main flume by constructing the branch V flumes very strongly, 
and using them much as a wet slide is used to slip the material, by 
the aid of the small amount of water available, from the higher ele- 
vations down to where a sufficient amount of water has accumu- 
lated to float it to its destination. 

SWITCHES AND Y'S. 

Switches and Y's are sometimes necessary in the lower end of a 
flume when it is desired to direct material to different points for piling 
or to a planing mill, if it be lumber, or to storage places if it be railroad 
ties, cordwood, or mining stulls, when, as sometimes occurs, the ship- 
ping or transportation facilities are not adequate to take care of the 
amount of material being handled daily by the flume. (See PI. V.) 
When this is the case and rough material is to be handled, it is advis- 
able to gradually raise the lower end of the flume on trestles, so as to 
have the desired space between the flume and the surface of the earth 



PLUMES AND PLUMING. 23 

to hold material diverted. Several switches or Y's scatter the 
material being shipped over whatever area it is designed to use as 
the storage place until such time as the material is to be manufactured 
or loaded onto railroad cars for transportation elsewhere. Plate V 
shows the general idea of the storage Y's. 

THE USE OF "SNUBS" IN UNLOADING MATERIAL FROM A FLUME. 

The use of a "snub" or temporary block in a flume so constructed 
that it will act as a dam which fills the flume to its utmost capacity 
and forces the material that is to be unloaded at this point to float at 
the highest possible elevation is often very useful in removing the 
material from the flume, particularly when it is desired to take it out 
over the side onto a loading platform alongside a railroad track, as 
shown in Plate VI, figure 1. The form of construction of a snub 
is shown in figure 6. With short, light material, such as railroad 
crossties, a snub under certain favorable conditions will throw the 
product being handled out of the flume without any assistance, 
although it is always good policy to have a man on hand to be sure 
that there will be no failure in getting the material out of the flume 
lest it cause a serious block or jam that may eventually break down 
the flume, and cause more expense than it would to keep a man on the 
job all the time. A form of snub working unassisted is shown in 
Plate VI, figure 2. 

REINFORCEMENT OF FLUMES AT POINTS WHERE EXTENSIVE LOADING 

IS TO BE DONE. 

Flume construction should usually be strongly reinforced at those 
points from which it is contemplated to do extensive shipping or 
where much material is to be loaded into the flume over the side. 
The constant pounding of material being dropped or thrown into the 
flume and striking on the sides of the V has a tendency to loosen the 
joints unless strengthened, and sometimes to break down the frame- 
work. In order to avoid this danger, it is usually advisable to place 
the bracket arms or frames and their attendant braces at shorter 
intervals or distances from each other at such points. 

Thus, if in the general flume line construction the arms and braces 
were placed at a distance of 8 feet apart, at the point where heavy logs 
or timbers are to be put into the flume it would be good policy to at 
least double the amount of brackets and braces or place them once in 
every 4 feet. If the timber to be loaded into the flume at this point 
were unusually heavy, it might be advisable to reduce the distance 
between the strengthening arms and braces still more. There are 
some cases where it has been found necessary to have the arms and 
braces every 2 feet at those points where the greatest amount of 
heavy material is loaded into the flume (see PI. VII, fig. 1) . It should 



2-4 BULLETIN 87, XJ. S. DEPARTMENT OF AGRICULTURE. 




Fig. 6.— A "snub ".in position for throwing small material out of a flume. 



Bui. 87, U. S. Dept. of Agriculture. 



Plate V. 




37, U. S. Dept. of Agriculture. 



Plate VI. 




Fig. 1.— A "Snub" in Operation, Throwing Crossties out of 
Flume at Railroad Landing by Pressure of Water. 

Man present to prevent material jamming. 




Fig. 2.— A "Snub" Working Alone. 



Qui. 87, U. S. Dept. of Agriculture. 




Plate VII. 


^HLfcjiife&f . i* 




4 


s«5^ Fjjjyafsli 




w*^-^58 




TS^^^Jn j 5 'xP 


■"ntSKS 


HH^ J '" J. 


8^ ' J§l&^fe -" 


fnjP^ 



Fig. 1 .— Brailing and Accoutring Lumber at the Upper End of a Flume. 

Note the sloping "ways" on which the brails are slid into the flume after being clamped. 




Fig. 2.— A "Mining Stull" Dump at the Lower End of a Flume where the 

Stulls are Run Directly Out of the " Vent" Ends. 
Note the several "vents" and the railroad spur tracks between the different flume "Y's." 



Bui 87, U. S. Dept. of Agriculture. 



Plate VI! 




Fig. 1.— A Flume in the Construction of which Small Round Timber was Used 
for Everything Except the "Box." 








Fig. 2.— Crude Form of Flume Construction where only the Lining is of 
Sawed Lumber, the Remainder being Constructed of Small Round Timber 
and Poles. 



FLUMES AND FLUMING. 25 

be understood, however, that the necessity for stronger bracing at 
different points of the flume depends largely, if not entirely, on the 
class of material being handled, and the prospective operator should 
be guided by this factor. 

TELEPHONES A VALUABLE ADJUNCT TO FLUME OPERATION. 

The use of the telephone in connection with fluming operations has 
been found a very necessary and valuable adjunct by its assistance 
to the operator in a great many ways. By its use it is possible to 
know just what is going on at the different points along the flume 
where " stations" are maintained, and notification of a serious jam or 
break in the flume can be quickly transmitted to the head of the 
flume and the shipping of material stopped. Otherwise it might be 
continued for a considerable length of time or until it was possible 
to get word to the upper end of the flume, and before this could be 
accomplished and the shipping stopped the break or block might 
become of such magnitude that to get the material back and repair 
the flume would cost almost as much as installing a telephone system. 
Telephone wires have sometimes been strung along and attached to 
the sides of flume construction, but this method is not considered 
generally satisfactory, as there is always the danger that w*hen the 
flume becomes jammed or is broken down the line may also be put 
out of commission at the very time when its assistance is most 
needed. It is generally more advisable to have the telephone wire 
strung on independent poles or convenient trees where the line runs 
through a forest than to have it attached to the framework or sides 
of the flume. 

By the use of the telephone it is possible to notify the shipper at 
the upper end of the flume what class of material to ship, when to 
ship it, and to keep in touch with what is going on along the flume 
line at all times. If there be a mill operating at the upper end of 
the flume, it is often very important that the employees at both 
ends of the line know exactly what class of material is going to be 
handled, since for a certain length of time one class might be going 
to a railroad landing to be loaded onto cars for shipment, after which 
for the remainder of the day a class of material might be shipped that 
should be turned by a switch into the storage pile, or vice versa. The 
valuable aid in fluming operations obtained through the use of the 
telephone usually makes its installation as an integral part of the 
plant most advisable. 

SAWED MATERIAL FOR STRINGERS, SILLS, BRACES, ETC., NOT A NECES- 
SITY BUT USUALLY MORE ECONOMICAL. 

It is not actually necessary that the material used in flume construc- 
tion, with the exception of the lumber for the "box" or body of the 
flume, should all be sawed. A number of flumes have been con- 



26 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

structed and successfully operated where the only sawed lumber 
used was that for the box, the trestling, sills, crosspieces, stringers, 
arms, and braces all being made from round poles flattened so as to 
fit solidly in the construction work. This method of construction is, 
however, often more expensive than to use the sawed material, where 
the latter can be economically obtained and cut into proper lengths 
by a power saw. 

The use of poles or small round material usually makes it necessary 
to cut the braces, arms, etc., into the desired length and form by hand 
power, and the increased cost of the manual labor necessary in such 
cases usually more than counterbalances the expense of having the 
material sawed at a mill, when this can be done without prohibitory 
expense. Existing conditions should always decide what method of 
construction will be most advisable. Illustrations of flumes where 
onlv the "box" was constructed of sawed lumber are shown in Plate 
VIII. 

WATER USED IN FLUMING SOMETIMES AVAILABLE FOR IRRIGATION 

PURPOSES. 

In some localities in the western country where irrigation is nec- 
essary, it will be found possible to utilize the water brought out from 
the mountains by the aid of a flume for irrigation purposes after it 
has served its purpose as the transporting medium for logs, timber, 
or lumber. 

Where there is a possibility of using the water for irrigation, it 
may be found advisable to construct a flume on a larger scale than is 
absolutely necessary for the simple transportation of the lumber and 
timber, in order to increase the amount of water available for irriga- 
tion purposes. This is a feature that should be carefully considered 
by the prospective operator when local conditions are such that a 
combination of the two different uses of the water can be made 
remunerative. 

BRAILING AND ACCOUTRING LUMBER. 

Where sawed lumber is being shipped for a long distance in a flume, 
it has in some cases been found advisable to brail or clamp a number 
of the boards, planks, or other material together, in order to make a 
compact body and thus reduce to a minimum the danger of forming 
jams and injuring the material being transported. It has also been 
found advisable to accoutre or hitch several of the "brails" together, 
by the use of short sections of shingle twine, wire, or other form of 
attachment, between the different clamped or brailed blocks of sawed 
lumber. In practice it is customary to pile from 10 to 20 boards or 
planks, usually aggregating about 200 feet, in a block at the mill or 
point where the shipping is being done. The size of the brail depends 
on the size of the flume and the class of material being shipped. 



FLUMES AND FLUMING. 27 

A metal clamp of the general form, shown in figure 7, is then slipped 
over the ends of the brail, and a dry wooden wedge, which can be 
quickly and cheaply constructed by the use of power saw in the mill, 
is driven into the end of the brail between the boards or planks, 
thereby forcing the lumber up against the teeth on the clamp and 
holding the whole body firmly in the position in which it was placed 
before being clamped. The twine is attached to the iron clamps on 
the front and rear ends of the respective brails to be shipped, and 
when a sufficient number have been prepared they are released in the 
flume, the weight and momentum of each one tending to keep its 
fellow, to which it is attached, following it in proper position, and 
preventing each one from running alongside the other and wedging 
or piling on the curve. The weight and momentum of the forward 
brail has a tendency to pull the following brail into line and thus 
maintain the average momentum of the whole body. This principle 
can be applied to sawed timbers, using staples and rope or wire to 
hold them in proper position. Several brails are usually accoutred 
together by the use of the tarred rope, shingle twine, wire, or other 
means of attachment. 

Upon arrival at the lower end of the flume the wedges are with- 
drawn, the lumber is released from the brail, and the " clamps" are 
hauled back to the head of the flume to be used again. This method 
of consolidating the shipments has been found particularly advisable 
for use on long, comparatively flat grade flumes, as it reduces very 
materially the amount of supervision or number of flume walkers 
necessary to keep the material running from what would be required 
if it were shipped separately, and prevents the timber from being 
split, broken, and battered on the ends or otherwise injured as much 
as when shipped in "loose" board form. Figure 7 shows the method 
most commonly used in brailing and accoutring material, and a form 
of clamp. 

PLANING MILLS SHOULD BE LOCATED AT LOWER END OF FLUME. 

As a general proposition the planing of sawed lumber which it is 
necessary to transport in a flume should be done only after the flum- 
ing process is completed, since fluming lumber after it is planed usually 
results in more or less discoloration of the surface, which is also liable 
to be marred in transit, thus injuring its sale value. 

SIZE AND CARRYING CAPACITY OF FLUMES FOR DIFFERENT CLASSES 

OF MATERIAL. 

The most advisable size of a flume for successfully transporting 
different classes of material depends on such factors as the grade, 
volume of water available, length of flume, etc. The class of mate- 
rial to be handled is always the principal factor to be considered, and 



28 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 




PLUMES AND FLUMLNG. 29 

upon this should depend largely the decision of what type or size of 
flume should be constructed. The capacity of a 24-inch V-shaped 
flume 10 miles in length, operated on a grade that was neither very 
flat nor exceptionally steep, with plenty of water, has been demon- 
strated as being capable of handling 25,000,000 feet b. m. of railroad 
cross ties and lumber per annum, under especially favorable conditions. 

For handling small material, such as railroad crossties, cordwood, 
mining stulls or props, and loose lumber, a 30-inch V-shaped flume 
(inside measurement) will usually be found of sufficient capacity for 
most any requirement, provided the grade is neither too flat nor too 
steep. Where either of these exceptions obtain, the size of the 
flume should preferably be increased to 36 to 40 inches. 

For a log flume nothing less than a 36-inch V-shaped flume should 
be built, and a 40 to 60 inch V would be preferable, even for medium- 
sized logs, if there is a sufficient volume of water available. To oper- 
ate a log flume successfully and economically there should be a suffi- 
cient volume of water available to fill the flume three-fourths full on 
all moderate grades. It will be apparent that if the grade of a large 
log flume were very steep, a very large body of water would be 
required. The larger, longer, and heavier the material to be han- 
dled, the larger the size of the V should be, the lesser degree of curva- 
ture is permissible, and the stronger must be the construction work. 

Tables showing the approximate amount of water in cubic feet 
required to fill a V-shaped flume on steady grades of different per 
cents will be found in another portion of this bulletin. 

COST OF TRANSPORTING DIFFERENT CLASSES OF MATERIAL. 

The cost of transporting material by flumes varies greatly accord- 
ing to the conditions under which the flume is being operated, the 
class of material, time of year, number of men necessary to operate 
the flume, and all the other factors that go to make up or reduce the 
expense of operation. Railroad crossties have been flumed a distance 
of 20 miles at an actual cost for operation alone of one-half cent per tie, 
or 15 cents per thousand; sawed lumber in cants of from 2 to 6 inches 
in thickness at approximately the same rate. 

If a flume line is properly constructed on a favorable and steady 
grade where it can be operated with a plentiful supply of water, the 
actual cost of transportation alone is very slight after the flume is con- 
structed. But the important fact should not be lost sight of that a 
flume works only in one direction and that all supplies intended to be 
used in lumbering operations have to be hauled to the head of the 
flume by animal or other power. 



30 BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 

COST OF CONSTRUCTION. 

The cost of constructing flumes will also vary a great deal with the 
conditions existing in the locality, the cost of lumber, cost of nails, 
and price of labor. In localities where it is possible to get a boiler, 
engine, and mill to the upper end of a proposed flume line cheaply 
and without being compelled to go to the expense of constructing a 
costly road, where there is plenty of timber easily accessible to the 
mill, which can be cheaply manufactured into lumber for purposes of 
construction, with low-priced labor, a flume can be constructed much 
more economically than in a locality where all these conditions were 
just the contrary. Rough lumber suitable for the construction of a 
flume can ordinarily be cut and fitted for construction work at a price 
varying from $7.50 to $10 for manufacture alone, exclusive of stump- 
age value. 

So much depends upon the locality in which a flume is to be con- 
structed, the price of labor, and the facilities for getting the necessary 
construction material cheaply, that it is impracticable to attempt any 
very close estimate on the total cost of any flume until all of the sur- 
rounding conditions are thoroughly understood . But in general, under 
favorable conditions, with a basis of $2.25 per diem for common labor 
and from $3.50 to $4 per diem for carpenters, not including board, 
suitably prepared lumber should be built into a flume for about $7.50 
per thousand. This would be about the minimum figure, and the 
cost would be liable to range upward from this price to $12 or higher, 
according to the conditions and prices of labor. 

The cost of the construction of the Bear Canyon flume in Montana, 
a 26-inch V 10 miles long, was approximately $2,000 per mile. The 
lumber cost $8.50 per thousand to manufacture and fit it for con- 
struction purposes, and it required about 100,000 feet b. m. to the 
mile. The labor cost $800 per mile, and $350 per mile was expended 
for nails, iron for trusses, and for cost of surveying. This flume was 
constructed a number of years ago when the cost of material and 
labor was less than it is to-day. 

A flume constructed from Dayton to Woodrock along the Tongue 
River, in the Bighorn National Forest, Wyo., is said to have cost 
approximately $3,500 per mile, in round figures, the cost of different 
sections varying from $2,500 to $7,500 per mile. This was a 30-inch 
V flume. There was considerable rock work on this line; Granite 
Canyon had to be passed through, where in some localities the flume 
was practically pinned to the sides of the canyon walls; there were 
several rock tunnels to be made through projecting points; and there 
were necessarily some very high trestles to be constructed. Another 
difficult feature of the construction of this flume was that of build- 



PLUMES AND FLUMING. 31 

ing the line across several miles of very soft, spongy ground with an 
almost flat grade to contend with. This flume was also constructed 
several years ago when the prices of labor and material were not, in 
general, so high as at the present time. 

Probably one of the best examples of modern V-shaped log-flume 
construction is a flume recently constructed on Rochat Creek, near 
St. Joe, Idaho. This flume, which is unusually large and strongly 
constructed for the purpose of handling large, heavy logs, and long 
timbers, is said to have cost approximately $8,000 per mile for the 
5 miles of its length. This figure includes the cost of construction 
of a wagon road and telephone line equipment. 

DISTANCE BETWEEN BENTS. 

There is a decided difference in the opinion of different operators 
as to the 'distance that the bents should be placed apart in flume 
construction, some contending for a 16-foot bent or length of stringers 
and box on all tangents, while others favor a 12-foot bent. Each has 
its merits. If a cheap flume for temporary use and medium capacity 
is desired, then one with 16-foot bents and boxes will usually answer 
the purpose; that is to say, if the life of the flume is only desired to be 
from 4 to 6 years. If large material is to be handled and the life of 
the flume is to be for a long period of time, then the construction 
work should be stronger and more lasting. If heavy material is to 
be handled, even the 30-inch V box flume might well be constructed 
with bents 12 feet apart, and in some cases even less if durability and 
strength are essential features. 

The trouble with the bents 16 feet apart usually is that the stringers 
are more apt to sag or twist, thereby letting the box sag on one side 
or the other. This usually causes the water in the flume to slop 
over at the point of sagging, and the water softens and washes out the 
foundations under the bents, so that eventually the section of the 
flume where this occurs becomes uneven in grade and therefore 
leaky. The result is that the work of repair is much increased and 
breakdowns in the transportation operations are more frequent. It 
is usually advisable to place the brackets or arms not more than 4 
feet apart on any size or style of flume. When placed farther apart 
than this it usually permits of too much spring to the box boards, 
and springing means leaks, which wash out the foundation of the 
bents and in many kinds of soil, especially on side hills, causes 
expensive slides or washouts. 

The same general principle applies in connection with the lining of 
a box, and there is much difference of opinion on the value of the 
different types of construction. It is contended by some operators 
that the 1^-inch box lining, strengthened with 1 by 4 inch battens 



32 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



firmly nailed over the joints on the outside, is much more satisfac- 
tory than the doubled 1-inch boards. It is contended that the 1-inch 
doubled box is not as rigid as the 1^-inch lining reinforced by the 
battens, and that the doubled box permits of a constant spring when 
heavy timber is passing through the flume. This causes the boards 
gradually to work apart and fill in between the two courses with 
bark and sediment, eventual!}' causing the box to leak badly. 

Another contention is that in relining there is never a good solid 
foundation to nail to, and that the nails keep working loose and 
catching passing timber, causing jams. It is claimed that, by the 
use of the 1^-inch or 2-inch box lining reinforced by the battens 
nailed on from the outside, the element of "spring" is materially 

reduced. 

ADVISABLE METHOD OF NAILING. 

In the construction of either type of box or the nailing on of the 
battens, the nails should, whenever possible, be driven from the 
outside and clinched on the inside of the box with the point of the 
nail turned down the flume. By so doing the nails become tighter 
as the inside of the box wears, since the flumed material strikes the 
nails and drives or draws them in harder. When the inside of the 
box is so badly worn that it is necessary to replace the lining, the new 
lining furnishes a solid substance through which to nail. Each style 
of construction has its particular merits, and the prospective opera- 
tor should decide for himself which is more applicable to his needs. 

Tables showing approximate amount of material necessary to con- 
struct flumes of different sizes follow: 

Table 1. — Weight of water in a 16-foot section of flume when filled to various depths. 





Weight of 




Weight of 




Weight of 




water in a 




water in a 




water in a 


Slant depth. 


section of 


Slant depth. 


section of 


Slant depth. 


section of 




flume 16 




flume 16 




flume 16 




feet long. 




feet long. 




feet long. 


Inches. 


Pounds. 


Inches. 


Pounds. 


Inches. 


Pounds. 


20 


1,390 


34 


4. mo 


4S 


7,990 


22 


1,680 


36 


4,490 


50 


8, 670 


24 


2,000 


38 


5,010 


52 


9,360 


26 


2,350 


40 


5,540 


54 


10, 100 


28 


2,710 


42 


6,110 


56 


10,900 


30 


3,110 


44 


6,740 


58 


11,700 


32 


3, 560 


46 


7,300 


60 


12,500 



Bui. 37, U. S Dept. of Agriculture. 



Plate IX. 




PLUMES AND FLUMING. 33 

Table 2. — Amount of water required to fill flumes to various depths at different grades. 





Gr*d* — per cent. 


Slant depth 
(inches). 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


14 


16 


13 


20 














Flow — Cubic feet per second. 








* 




20 


10 

13 

16 

20 

24 

29 

35 

41 

48 

55 

63 

72 

81 

91 

102 

115 

127 

140 

156 

170 

186 


14 

18 

23 

28 

34 

41 

49 

58 

67 

78 

89 

101 

114 

130 

144 

161 

179 

198 

220 

241 

262 


17 

22 

28 

34 

42 

50 

60 

71 

82 

95 

109 

127 

140 

158 

177 

198 

219 

242 

269 

295 

322 


19 

25 

32 

40 

48 

58 

69 

81 

95 

110 

125 

143 

163 

183 

205 

228 

253 

281 

311 

339 

372 


22 

28 

36 

45 

54 

65 

78 

91 

107 

123 

140 

160 

181 

204 

230 

255 

283 

313 

348 

380 

415 


24 

31 

39 

49 

59 

71 

85 

100 

117 

135 

154 

175 

199 

223 

251 

279 

311 

342 

383 

415 

455 


26 

33 

42 

53 

64 

77 

92 

108 

126 

145 

166 

189 

214 

241 

271 

302 

336 

371 

412 

449 

492 


28 

36 

45 

56 

6& 

82 

98 

115 

131 

1S6 

178 

203 

229 

258 

290 

323 

358 

396 

440 

481 

525 


29 

38 

48 

60 

72 

87 

104 

122 

143 

165 

189 

215 

243 

274 

307 

343 

381 

421 

467 

510 

558 


31 

40 

51 

63 

76 

92 

109 

129 

150 

174 

199 

226 

257 

289 

323 

360 

401 

443 

492 

537 

589 


32 

42 

53 

66 

80 

96 

115 

136 

158 

182 

209 

237 

269 

302 

340 

378 

420 

465 

517 

564 

616 


34 
44 
55 
69 
84 
101 
120 
142 
165 
190 
218 
248 
281 
316 
354 
397 
440 
484 
538 
589 
644 


36 
47 
60 
74 
90 
109 
130 
153 
178 
206 
235 
267 
303 
341 
383 
428 
475 
524 
583 
636 
695 


39 
51 
64 
79 
96 
116 
138 
163 
190 
220 
251 
286 
325 
365 
410 
456 
507 
560 
621 
681 
744 


41 
54 
68 
84 
102 
123 
147 
173 
202 
233 
266 
304 
344 
387 
434 
483 
537 
594 
661 
721 
788 


43 


22 


56 


24... 


71 


26 


89 


28 


108 


30 

32 


130 


34 


183 


36 


212 


38 


245 


40 


281 


42 


319 


44 


362 


46 


408 


4S 


458 


50 


510 


52 


567 


54 


626 


56 


697 


58 


759 


60 


831 







Table 3. — Velocity of water in flumes when filled to various depths at different grades. 



Slant depth 
(inches). 



Grade— per cent. 



16 18 20 



Velocity of water — Miles per hour. 



20 
22 
24 
26 
28 
30 
32 
34 
36 
38 
40 
42 
44 
46 
48 
50 
52 
54 
56 
58 
60 



5 


7 


8 


9 


11 


12 


13 


13 


14 


15 


16 


17 


18 


19 


20 


5 


7 


9 


10 


11 


13 


14 


14 


15 


16 


17 


18 


19 


21 


22 


5 


8 


9 


11 


12 


13 


14 


15 


16 


17 


18 


19 


20 


22 


23 


5 


8 


10 


12 


13 


14 


15 


16 


17 


18 


19 


20 


22 


23 


24 


6 


9 


10 


12 


14 


15 


16 


17 


18 


19 


20 


21 


23 


24 


26 


6 


9 


11 


13 


14 


16 


17 


18 


19 


20 


21 


22 


24 


25 


27 


7 


9 


11 


13 


15 


16 


18 


19 


20 


21 


22 


23 


25 


27 


28 


7 


10 


12 


14 


15 


17 


18 


20 


21 


22 


23 


24 


26 


28 


29 


7 


10 


12 


14 


16 


18 


19 


20 


22 


23 


24 


25 


27 


29 


31 


7 


11 


13 


15 


17 


18 


20 


21 


22 


24 


25 


26 


28 


30 


32 


8 


11 


13 


15 


17 


19 


20 


22 


23 


24 


26 


27 


29 


31 


33 


8 


11 


14 


16 


18 


20 


21 


23 


24 


25 


26 


28 


30 


32 


34 


8 


12 


14 


16 


18 


20 


22 


23 


25 


26 


27 


29 


31 


33 


35 


8 


12 


15 


17 


19 


21 


22 


24 


25 


27 


28 


29 


32 


34 


36 


9 


12 


15 


17 


20 


21 


23 


25 


26 


28 


29 


30 


33 


35 


37 


9 


13 


16 


18 


20 


22 


24 


25 


27 


28 


30 


31 


34 


36 


38 


9 


13 


16 


18 


21 


23 


24 


26 


28 


29 


31 


32 


35 


37 


39 


9 


13 


16 


19 


21 


23 


25 


27 


28 


30 


31 


33 


35 


38 


40 


10 


14 


17 


19 


22 


24 


26 


28 


29 


31 


32 


34 


36 


39 


41 


10 


14 


17 


20 


22 


24 


26 


28 


30 


31 


33 


34 


37 


40 


42 


10 


14 


18 


20 


23 


25 


27 


29 


30 


32 


34 


35 


38 


41 


43 



34 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



In the preparation of these tables the formula v = c-yjr s was used, 
in which v = the velocity of the water in feet per second, c = a con- 
stant, r = the hydraulic radius in feet, and s = the slope. Each step 
was carried out to three significant figures. The following values for 
c and r were used : 



Slant depth. 


c 


r 


Slant depth. 


c 


r 


Slant depth. 


c 


r 


Inches. 






Inches. 






Incites. 






20 


108 


0.417 


34 


121 


0.708 


48 


128 


1.00 


22 


111 


.458 


36 


122 


.750 


50 


129 


1.04 


24 


113 


.500 


38 


123 


.792 


52 


130 


1.08 


26 


115 


.542 


40 


124 


.833 


54 


131 


1.12 


28 


116 


.583 


42 


125 


.875 


56 


132 


1.17 


30 


118 


.625 


44 


126 


. .917 


58 


132 


1.21 


32 


119 


.667 


46 


127 


.958 


60 


133 


1.25 



This formula is based upon experiments with slopes of less than 
10 per cent, and while its application to steeper grades has not been 
thoroughly checked by actual determinations of velocity, the results 
are considered sufficiently accurate for use in the design of timber 
flumes. 

Table 4. — Estimate of approximate amount of material required for construction of 

flumes. 

26-INCH "V" FLUME WITH lJ-FNCH BATTENED BOX. 



Kinds of lum- 
ber. 



Mud sills 

Posts 

Caps 

Braces, sway... 
Braces, lateral.. 

Stringers 

Sills 

Braces 

Arms 

Box boards. . .. 

Battens 

Running boards 



Add for waste. 
Total.... 



Lumber required per mile. 



Dimensions. 



Inches. 
4 x 
4 x 
4 x 
1 x 
1 x 
4 x 
2£x 
2£x 
2Jx 
l|x54 
1 x 4 
HxlO 



Ft. in. 
7 3 



7 

3 

9 

7 
16 

4 

11 

2 2 
16 

5 
16 



Ft. in. 



( 2 ) 



Ft. in. 
9 I 
19 '. 
4 ? 



10 10 

108 

20 

20 



330 

660 

330 

660 

i 1,100 

660 

990 

1,980 

1,980 



3,960 
330 



330 
330 
330 
330 
1275 
330 
330 
330 
330 
330 
330 
330 



*' a 



Nails required per mile. 



97, 103 

2,897 



100, 000 



Size. 


T3 




s 




O 




Ph 


10-penny.. 


763 


12-penny. . 


682 


16-penny. . 


113 


20-penny. . 


425 



One keg of 40-penny 
nails and 1 keg of 
60-penny nails should 
usually be allowed for 
such preliminary work 
as bridging, etc. 



Total....! 1,983 19] 



1 Lateral braces are only figured for five-sixths of a mile, as at least one-sixth of each mile, onanaverage, 
will be too close to the ground to require the use of these braces. 
- Various sizes. 



FLUMES AND FLUMING. 



35 



Table 4. — Estimate of approximate amount of material required for construction of 

flumes — Continued . 

30-INCH "V" FLUME WITH 1-INCH DOUBLE BOX. 



Kinds of lum- 
ber. 



Mudsills 

Posts 

Caps 

Braces, sway. 
Braces, lateral 

Stringers 

Sills 

Braces 

Arms 

Box boards. . 
Running boards 



Add for waste. 
Total... 



Lumber required per mile. 



Dimensions. 



Inches 
4 
4 
4 

1 X 
1 X 

4 x 
2}x 
2|x 
2* x 



6 

6 

x 6 

x 6 

x 6 

x 8 

5 

5 

5 

x62 
xlO 



Ft. in 
7 

7 3 

4 7 
9 2 
7 

16 

5 4 

1 1 

2 6 
16 
16 



Ft. in. 

15 4 

14 6 

9 2 

4 7 
3 9 

42 8 

5 6§ 

i n 

2 1\ 
( 2 ) 
20 



Ft. in. 

15 4 

29 

9 2 

9 2 

15 
85 4 

16 8 
6 9 

15 1\ 

165 4 

20 



330 
660 
330 
660 

n,ioo 

660 
990 

1,980 
1,980 



330 



330 
330 
330 
330 
i 275 
330 
330 
330 
330 
330 
330 



*13 



5,060 

9,570 

3,025 

3,025 

!4,125 

28, 160 

5, 500 

2,228 

5,157 

54, 560 

6,600 



135, 000 



Nails required per mile. 



Size. 






a 
















1—1 


10-penny.. 


500 


12-penny.. 


528 


16-penny. . 


948 


20-penny.. 


156 



li 



One keg of 40-penny 
nails and one keg of 
60-penny nails should 
usually be allowed for 
such preliminary work 
as bridging, etc. 



Total... 



2, 132 



21| 



30-INCH "V" FLUME WITH 1HNCH BATTENED BOX. 



Mud sills 

Posts 

Caps 

Braces, sway... 
Braces, lateral.. 

Stringers 

Sills 

Braces 

Arms 

Box boards 

Battens 

Running boards 



Add for waste. 
Total.... 



4x6 
4x6 
4x6 
1x6 
1x6 
4x8 



2*x 5 
2|x 5 
2Jx 5 
13rX62 

1x4 

UxlO 



7 8 

7 3 

4 7 
9 2 
7 6 

16 

5 4 

1 1 

2 6 
*6 

5 

16 



15 
14 

9 

4 

3 
42 

5 

1 

2 

( 2 ) 

1 
20 



330 
660 
330 
660 
i 1, 100 
660 
990 

1, 

1, 



3,960 
330 



330 
330 
330 
330 
1275 
330 
330 
330 
330 
330 
330 
330 



5,060 

9,570 

3,025 

3,025 

i 4, 12.5 

28,160 

5,500 

2,228 

5,157 

40,920 

6,600 

6,600 



119,970 
5,030 



125, 000; 




10-penny. . 
12-penny.. 
16-penny.. 
20-penny . . 



One keg of 40-penny 
nails and 1 keg of 60- 
penny nails should 
usually be allowed for 
such preliminary work 
as bridging, etc. 



Total. 



36-INCH "V" FLUME WITH H-INCH BATTENED BOX. 



Mud sills 

Posts 

Caps 

Braces, sway... 
Braces, lateral.. 

Stringers 

Sills 

Braces 

Arms 

Box boards 

Battens 

Running boards 



Add for waste. 
Total.... 



4x6 
4x6 
4x6 
1x6 
1 x 6 
4x8 
3x5 
3x5 
3x5 
l£x 74 
1x4 
H x 10 



G 
3 


7 6 
12 



10 



12 
4 



17 

14 6 

10 

5 

3 9 

32 



7 6 
1 9 
3 9 
( 2 ) 
1 4 
15 



17 

29 

10 

10 

15 

64 

22 6 

10 7J 

22 6 

111 

24 

15 



440 

880 

11,467 

880 

1,320 

2.640 

2,640 



7,920 
440 



440 
440 
440 
440 
1 366| 
440 
440 
440 
440 
440 
440 
410 



153, 175 
6,825 



160, 000 




10-penny. 
12-penny. 
16-penny. 
20-penny. 



One keg of 40-penny 
nails and one keg of 
60-penny nails should 
usually be allowed for 
such preliminary work 
as bridging, etc. 



Total.... 



3,218 



32J 



1 Lateral braces are only figured for five-sixths of a mile, as at least one-sixth of each mile, on an average, 
will be too close to the ground to require the use of these braces. 

2 Various sizes. 



36 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



Table 4. — Estimate of approximate amount of material required for construction of 

flumes — Continued . 

54-INCH "V" FLUME WITH 2-INCH BATTENED BOX. 



Kinds of lum- 
ber. 



Mud sills 

Posts 

Caps 

Braces, sway... 
Braces, lateral.. 

Stringers 

Sills 

Braces 

Arms 

Box boards 

Battens 

Running boards 



Add for waste. 
Total.-.. 



Lumber required per mile. 



Dimensions. 



Inches. 
6x6 
6 x 
6 x 
ljx 
Hx 
6"x 
4 x 
4 x 
4x6 
2 xllO 
ljx 4 
2 x 12 



Ft. in. 

10 
7 3 

7 

11 
7 6 

12 
7 
1 9. 1 
4 6' 

12 

4 

12 



Ft. in. 

30 

21 9 

21 

8 3 
5 V 

48 0' 

14 

3 7 

9 
( 2 ) 

1 S 

24 



Ft. in. 

30 

43 6 

21 
16 6 

22 6 
96 
42 
21 6 
54 

220 

40 

24 



440 

880 

440 

88i 

11,46 

880 

1,320 

2,640 

2,640 



10, 560 
440 



440 
440 
440 
440 
1366? 
440" 
440 
440 
440 
440 
440 
440 






13,200 

19, 140 

9,240 

7,260 

8,250 

42,240 

18, 480 

9,460 

23, 760 

96, 800 

17, 600 

10, 560 



275, 990 
9,010 



285,000 



Nails required per mile. 



Size. 



1,700 17 

1, 075 10J 

390 4 

3, 625 36J 



12-penny. . 
16-penny. . 
20-penny . . 
40-penny. . 



One keg of 40-penny 
nails and one keg of 
60-penny nails should 
usually be allowed for 
such preliminary work 
as bridging, etc. 



Total . 



i Lateral braces are only figured for five-sixths of a mile, as at least one-sixth of each mile, on an average, 
will be too close to the ground to require the use of these braces. 
2 Various sizes. 

o 



WASHINGTON : GOVERNMENT PRINTI NG OFFICE : 1814 




BULLETIN OF THE 



No. 88 




Contribution from the Bureau of Entomology, L. 0. Howard, Chief. 



April 30, 1914. 

THE CONTROL OF THE CODLING MOTH IN THE 
PECOS VALLEY IN NEW MEXICO. 

By A. L. Quaintance, in Charge of Deciduous Fruit Insect Investigations. 
INTRODUCTION. 

For some years complaints have been received by the Bureau of 
Entomology from the fruit growers in the Pecos Valley, N. Mex., of 
the severe injury to apples and pears by the codling moth (Carpocapsa 
pomonella L.). The methods employed in the control of this insect 
in other apple-growing regions have, in the Pecos Valley, been 
stated to be there much less efficient, so that a considerable portion 
of the crop of fruit has been wormy and unsalable. 

The codling moth should yield as readily to treatment in the Pecos 
Valley as elsewhere, though, owing to favorable climatic conditions, 
it was surmised that it might develop an additional generation. It 
was not believed, however, that the behavior of the insect in that 
region was essentially different from its behavior in other sections, 
and the lack of satisfactory results from spraying operations, it was 
thought, probably resulted from failure to accomplish this work in a 
thorough and timely manner. 

Beginning in the spring of 1912 an investigation of the codling 
moth was undertaken by the Bureau of Entomology, with head- 
quarters at Koswell, N. Mex., and Mr. A. G. Hammar, who had had 
much experience with this insect at other field stations of the bureau, 
was assigned to the work. During that year he was assisted by Mr. 
Earl R. Van Leeuwen, and during 1913 by Mr. L. L. Scott and Mr. 
E. W. Geyer. Owing to the unfortunate death of Mr. Hammar there 
devolves upon the writer the necessity of preparing for publication, 
for the benefit of the Pecos Valley fruit growers, the results of Mr. 
Hammar's experiments. The investigations carried out by Mr. 
Hammar comprise a thorough inquiry into the fife history and habits 
of the codling moth in that region, and experiments with sprays in 
orchards. The results of the life-history studies will be given in. 
another paper. 

Note. — This bulletin describes the codling moth as it affects fruit growing in the Pecos Valley, N. Mex. 
It is of interest to fruit growers in the Southwest. 

M853°— 14 



2 BULLETIN B8, T :. 5. DEPARTMENT OF AGRICULTUEE. 

The present article deals with results obtained in spraying in 1913. 
Work was carried out in two orchards, namely, that of Messrs. 
Sherman & Johnson and that of Mr. Robert Beers. Unfortunately 
the report of results in the latter orchard is not entirely complete, so 
that the details of these experiments can not be given. In general, 
however, the results obtained hi the Beers orchard agree with those 
secured in the Sherman & Johnson orchard, and the latter are given 
in detail in the following pages. 

EXPERIMENTS IN THE SHERMAN & JOHNSON ORCHARD. 

A portion of the Sherman & Johnson orchard, about 5 acres in 
extent, was selected for spraying experiments and was subdivided 
into plats, as shown in figure 1. 

The trees were large, and codling-moth conditions were fairly 
typical for the valley. Plat I received three applications: Plat II, 
four applications: and Plat III, five applications of arsenate of lead 
spray. Plat IV was left unsprayed throughout the season for pur- 
poses of comparison. A good power sprayer was used, capable of 
supplying three or four leads of hose, and maintaining a pressure of 
200 to 225 pounds. (See fig. 2, showing outfit in operation, and size 
of trees used.) Further information concerning the treatments and 
the dates of spray applications for the respective plats is given in 
Table I. 

Table I. — Treatments and dates of applications of sprays for codling moth, Sherman & 
Johnson orchard. Roswell, X. Mex., 1913. 



Dates of appli- 
cations. 



Plat I d applications). 



Apr. 24-25 

(After falling of 
petals. ) 



Mav 7-S. 



Arsenate of lead, G 
pounds to 200 gal- 
lons of water. Bor- 
deaux nozzles. 164 
gallons per tree! 
225 pounds pres- 
sure. 
Arsenate of lead, 8 
pounds to 200 gal- 
lons of water, ver- 
morel type nozzles. 
13 j gallons per tree. 
200 pounds pres- 
sure. 

June 16-17 Arsenate of lead, 8 

pounds to 200 gal- 
lons of water. \ er- 
morel type nozzles, 
lof gallons per tree. 



July 14-15. 



Aug. 2. 



Plat II (4 applica- 
tions). 



Plat III (5 applica- 
tions). 



Arsenate of lead. 6 
pounds to 200 gal- 
lons of water. Bor- 
deaux nozzles. 164 
gallons per tree. 
225 pounds pres- 
sure. 

Arsenate of lead, S 
pounds to 200 gal- 
lons of water. Ver- 
morel type nozzles. 
13J gallons per tree. 
200 pounds pres- 
sure. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water. Yer- 
morel type nozzles. 
15 \ gallons per tree. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water, ver- 
morel type nozzles. 
\~\ gallons per tiee. 



Arsenate of lead, 6 
pounds to 200 gal- 
lons of water. Bor- 
deaux nozzles. 16J 
gallons per tree. 
225 pounds pres- 
sure. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water. Ver- 
morel type nozzles. 
13 J gallons per tree. 
200 pounds pres- 
sure. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water. Ver- 
morel type nozzles. 
15J gallons per tree. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water. Ver- 
morel type nozzles. 
17J gallons per tree. 

Arsenate of lead, 8 
pounds to 200 gal- 
lons of water. \er- 
morel type nozzles. 
9J gallons per tree. 



Plat IV 
(unsprayed). 



Unsprayed. 



Do. 



Do. 



Do. 



CONTROL OF THE CODLING MOTH IN NEW MEXICO. 



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Fig. 1.— Diagram showing arrangement of trees used in codling-moth experiments, Sherman & Johnson 
orchard, Roswell, N. Mex. (Original.) 




Fig. 2.— Viewin Sherman & Johnson orchard, Roswell, N. Mex. , showing size of trees and power sprayer 

in operation. (Original. ) 



4 BULLETIN" 88, U. S. DEPARTMENT OF AGRICULTURE. 

It will be noted from Table I that the amount of spray used in 
all applications was large, and probably considerably in excess of 
that used by the average fruit grower in the valley. The amount 
of spray applied immediately following the falling of the petals 
(April 24-25) exceeded somewhat the amount given in any subsequent 
application. It will be noted also that Bordeaux nozzles were used 
at this time, whereas in subsequent treatments the so-called eddy 
chamber or Vermorel type of nozzle was used, producing a fine cone- 
shaped spray. 

In Table II are shown the number and percentage of sound fruit 
from each of five trees of each plat, as well as the total number and 
total percentage of sound and wormy fruit for the five trees of the 
respective plats. 

Table II. — Number of sound and wormy apples from each tree of each plat, Sherman 
& Johnson orchard, Roswell, JS T . Mex., 1913. 



Plat and condition of fruit. 


Tree 1. 


Tree 2. 


Tree 3. 


Tree 4. 


Tree 5. 


Total 

fruit 

for 

plat. 


Total 
per 
cent 
sound 
fruit. 


Plat I. 


138 
2,918 


141 
2,022 


153 
3,382 


179 
3,418 


152 
3,239 


706 
14, 979 




Sound 




Total 


3,056 
95. 48 


2,166 
93. 35 


3,535 
95.67 


3,597 
95.02 


3,391 
95.52 


15, 745 






95.13 






Plat II. 

Wormy 


86 
4,271 


39 
4,086 


33 
3,378 


37 
3,344 


70 
5,504 


265 
20,583 








Total 


4,357 
98.02 


4,125 
99.05 


3,411 
99.03 


3,381 
98.90 


5,574 
98.74 


20,848 




Per cent sound 


98.72 






Plat III. 

Wormy 

Sound 


51 
6,283 


18 
4,479 


40 
4,494 


25 

4,618 


14 

4,442 


148 
24,316 




Total 


6,334 
99.19 


4,497 
99.59 


4,534 
99.12 


4,643 
99.46 


4,456 
99.68 


24,464 


99.39 






Plat IV. 

Wormy 

Sound 


5,308 
2,871 


2,671 
2,349 


3,813 

2,873 


3,486 
2,765 


3,336 
1,958 


18,614 
12,816 




Total 

Per cent sound 


8,179 
35.12 


5,020 
46.79 


6,686 
42.97 


6, 251 
44.23 


5,294 
37.03 


31,430 


40.77 







It will be seen that Plat I, which received a total of three applica- 
tions of an arsenate of lead spray, gave 95.13 per cent sound fruit. 
Plat II, with four applications, yielded a somewhat higher quantity 
of sound fruit, namely, 98.72 per cent; while from Plat III, which 
received five spray applications, 99.39 per cent of the fruit for the 
season was sound. Plat IV, which was not spra}*ed during the 
season, shows only 40.77 per cent of the fruit free from codling moth 
injury. In determining these results, examinations were made as 
to worminess of all the apples produced on the five count trees 
Ithroughout the season; that is, the fruit which fell, the fruit which 
was picked from the trees in thinning, and that picked at harvest time. 



CONTROL OF THE CODLING MOTH IN NEW MEXICO. 5 

It would appear that with the minimum of three applications, 
made as shown in Table I, injury from the codling moth in the Pecos 
Valley may be reduced to less than 5 per cent of the total crop of 
apples produced. For each of the two additional applications an 
increase in sound fruit is shown, but probably not in proportion to 
the expense involved. It should be borne in mind, however, that in 
these experiments applications were made with much thoroughness, 
and unless the orchardist will do equally as thorough work it will be 
better for him to make the additional applications. 

PLACES OF ENTRANCE OF FRUIT BY CODLING MOTH LARVAE. 

Many observations in different parts of the country have shown 
that the majority of codling moth larvae normally enter the apple at 




Fig. 3.— Showing condition of calyx lobes of Ben Davis apple: o, Two days after falling of petals; b, ten 
days after falling of petals. (Original.) 

the calyx end. A careful study of the places of entering sprayed 
fruit by larvae, whether at calyx, side, or stem, throws much light 
on the relative effectiveness of the respective spray applications. 
All experiments corroborate the statement that the treatment given 
immediately after the falling of the petals is by far the most im- 
portant one and that its omission can not be corrected by subsequent 
treatments, however thoroughly made. 

A study of the behavior of the calyx lobes of the recently set 
apples in the Roswell section furnishes evidence of value in timing 
spray applications. Ordinarily in the East there is a period of about 
10 days following the dropping of apple blossoms during which the 



I 1 . 



BULLETIN 88, U. S. DEPARTMENT OF AGRICULTURE. 



calyx lobes remain open, so that the spray may be successfully 
directed into the calyx cups. In New Mexico, however, it would 
appear that the calyx lobes of the little apples do not draw together 
nearly so quickly after the falling of the petals and may remain 
open in suitable condition for calyx spraying for a period of from two 
to three weeks, varying somewhat with the variety and season. 
(Figs. 3 and 4.) 

This condition renders it possible to apply the second spray in a 
way to supplement the first spray into the calyx cups. 




Fig. 4.— Showing condition of calyx. lobes of Ben Davis apple: a, 18 days after falling of petals; 6, 30 
days after falling of petals. (Original.) 

The effect of spraying in changing the relative proportion of larvae 
which succeed in entering the fruit at the calyx, side, and stem is 
shown for Plats I to III in Table III. The normal behavior of the 
larvae in entering the fruit may be seen by referring to the figures for 
Plat IV of this table. It will be noted that on the unsprayed plat 
somewhat over one-half (53.72 per cent) of the total larvae for the 
season entered the fruit at the calyx end. 

Table III. — Number and percentage of codling moth larvse entering fruit at calyx, side, 
~and stem for Plats I- IV, Sherman & Johnson orchard, Roswell, N. Mex., 1913. 



Total larva; for plat for season en- 
tering at — 


Plal 

I. 


Per cent. 


Plat 

11. 


Per cent. 


riat 

III. 


Per cent. 


Plat 
IV. 


Per cent. 




19 

789 
10 


2.31 

96.45 

1.24 


17 
249 

5 


6.27 

91.88 

1.85 


10 

128 

10 


6.76 
86.48 
6.76 


12,663 
9,622 
1,285 


53. 72 


Side 


40.82 


Stem 


5.46 






Total 


818 


100. 00 


271 


100.00 


148 


ioo. oo 


23, 570 


100. 00 







CONTEOL OF THE CODLING MOTH IN NEW MEXICO. 7 

This table also shows the destructive influence of sprays in lessening 
the actual number of larvse. Thus on Plat I, which received three 
sprays, there was a total of 818 larvse for the season, on the five 
count trees; on Plat II, which received four sprays, the number of 
larvse for the five trees was 271; while on Plat III, which received 
five sprays, only 148 codling moth larvse were found in fruit from the 
five "count trees" during the year. The foregoing figures are in 
marked contrast with the total number of larvse found in fruit from 
the five unsprayed trees, namely, 23,570. 

RECOMMENDATIONS BASED ON THE FOREGOING RESULTS. 

While the results reported herewith are very clear-cut, the bureau 
would not be warranted in formulating definite recommendations 
based upon the work thus far carried out in the Pecos Valley were it 
not for the reason that these results substantiate the results obtained 
from a large series of spraying experiments against the codling moth 
in many parts of the United States. In Table I, showing treatments 
and dates of applications, the reader will note that the first applica- 
tions were made with Bordeaux nozzles and the. later applications 
with eddy chamber nozzles. Entomologists of certain Western States 
who have experimented with the codling moth under arid conditions 
insist upon the advantage of a coarse spray given at the time imme- 
diately following the dropping of the petals. Tests of the compara- 
tive value of coarse and fine sprays under eastern conditions show 
that there is apparently but little difference as regards the effective- 
ness in the control of the insect of a coarse and fine spray. The 
Roswell experiments did not include a comparison of coarse and fine 
sprays and no specific information can be furnished on this point, 
and it would appear safer for the orchardist to follow the methods 
used by Mr. Hammar until further information is obtained. It will 
also be noted that spraying was done under high pump pressure. 
This should not be construed to mean that effective work in the con- 
trol of the codling moth can not be accomplished except by use of 
power outfits working at high pressure. Very good results have been 
obtained from the use of barrel sprayers working at perhaps 100 to 
120 pounds pressure. 

The prime essential in the control of the codling moth is that the 
treatment given immediately after the falling of the blossoms shall 
be made with great thoroughness, in order to insure the lodgment of 
poison in the calyx cup of each and every apple. This result is best 
secured by so handling the spray rods that the spray is directed 
downward into the upright clusters of the little apples. This spray- 
ing especially should be made rather deliberately and with great 
pains. Frequent examination of sprayed trees should be made to 
determine how thoroughly calyx cups are being filled with poison. 



8 BULLETIN 88, U. S. DEPARTMENT OF AGRICULTURE. 

First application. — As soon as the petals have fallen, spray the 
trees with arsenate of lead, using the poison at the rate of 6 pounds 
to 200 gallons of water. Direct the spray straight into the calyx 
cups, for which purpose an elbow or crook should be used on the end 
of the spray rods. In spraying high trees a tower is indispensable, 
as shown in figure 2. 

Second application. — About two weeks after the falling of the petals 
spray with arsenate of lead at the rate of 8 pounds to 200 gallons of 
water. Make an effort to apply this spray before the calyx lobes are 
more than three-fourths closed, which may be determined by careful 
examination in the orchard. (See fig. 3.) Direct tins spray, also, as 
much as possible straight into the calyx cups, and at the same time 
take care to coat the leaves and fruit. 

Third application. — Eight or nine weeks after the falling of the 
petals spray again with arsenate of lead at the rate of 8 pounds to 200 
gallons of water. In this treatment cover the foliage and fruit as 
uniformly as possible with the poison. 

Subsequent applications. — The three applications specified, if thor- 
oughly made, should effectively control the codling moth, as shown 
by the results of experiments herewith reported. If these applica- 
tions have not been thoroughly made, and it is seen that the codling 
moth will do considerable injury, additional applications will doubt- 
less be desirable to check the insect as much as possible. Thorough 
work, especially in applying the first and second applications, should 
largely obviate the necessity for more than three treatments. 



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Or THIS PUBLICATION MAY BE PEOCURED FROM 

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AT 

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\7 




BULLETIN OF THE 



No. 89 




Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 
May 22, 1914. 

(PROFESSIONAL PAPER.) 

THE DEATH OF CHESTNUTS AND OAKS DUE TO 
ARMILLARIA MELLEA. 

By W. H. Long, 
Forest Pathologist, Office of Investigations in Forest Pathology. 

INTRODUCTION. 

Some time ago complaint was made to the Office of Investigations 
in Forest Pathology that the chestnut trees on certain areas near New 
Berlin, in Chenango County, N. Y., were rapidly deteriorating; that 
some were dead, others dying, and the remainder in poor health. Since 
this region is not in the known range of the chestnut bark disease 
(Endothia parasitica), the dying of the chestnut could not be attrib- 
uted to this fungus, and the writer was therefore detailed to make an 
investigation of the trouble. 

CHARACTER OF THE TIMBER EXAMINED. 

Two areas of woodland of about 20 acres each were examined. 
The timber consisted of a mixed stand of chestnut, oak, and white 
pine, with a sprinkling of poplar, maple, and hemlock. All of the 
timber above a diameter of 6 inches, or even less, was being cut. 
Much of it had only recently been felled, while some was still uncut. 
The oak and chestnut were being made into railroad ties and the pine 
into lumber. Both tracts of timber were located on the level tops 
and slopes of rather rough ridges. The average age of the chestnut 
and oak was from 60 to 100 years. One of the areas had been partially 
logged over 20 years ago; the other had never been logged. There 
have been no forest fires in either tract, so far as known. As the 
two areas were close to each other and similarly located, they will 
be treated as a whole in this discussion. 

CHARACTER OF DATA OBTAINED. 

In addition to the felled trees of chestnut and oak, dead, dying, 
and badly diseased standing trees were studied. No attempt was 
made, on account of limited time, to examine the roots of any number 

Note.— A record of the results of field investigations of the condition of chestnut and oak in Chenango 
County, N. Y. 

34907*— 14 1 



2 BULLETIN" 89, TJ. S. DEPARTMENT OP AGRICULTURE. 

of living trees. A record was kept of each felled and each dead tree. 
The data taken included the diameter of stump, the average height of 
stump (which was usually about 1 foot), the diameter of the rot in the 
stump, the height to which the rot ascended in the butt of each tree, 
the cause of each kind of rot found, the root-rots present, the number 
of dead trees, the cause of death, the number of dead trees blown 
down, and any other facts bearing on the health of the trees. Data 
on 902 felled trees were obtained. Of this number, 477 were white 
oaks, 302 chestnuts, 61 red oaks, 45 poplars, and the remainder 
maples, service berries, and pines. 

GENERAL CONDITION OF THE CHESTNUT. 

HEALTH OF THE TREES. 

All of the chestnut trees over 18 inches in diameter were found to 
have diseased tops; that is, some were " stag headed, " while all had 
one or more large dead branches on them. Many of the larger 
chestnut trees, especially those somewhat isolated on the edges of 
the ridges, had been struck by lightning. These trees were not 
killed outright, but in many cases tops, branches, and strips of bark 
of varying sizes had been killed. In a few instances the bark had 
been partially stripped from the tree, but usually the lightning left 
little or no external evidence of immediate injury. A careful exam- 
ination, however, showed that wide strips of bark had been killed, 
especially near the bases of the trees, and that little or no callus had 
formed around the wounds. In the majority of cases the wounds 
had not healed, but were gradually increasing in size. This increase 
was always greater at the base of the tree and could usually be traced 
directly to the parasitic action of the fungus Armillaria mellea. The 
typical rhizomorphs, or "shoe strings," of this fungus were present 
at the bases of the trees and extended 5 to 20 feet upward beneath the 
bark. 

Of the tops, 75 per cent were infected by a pocketed or piped rot 
(PI. I, fig. 1) caused by the fungus Polyporus pilotae, which had 
apparently entered through the old dead branches so common on 
the upper parts of chestnut trees in this region. In addition to this 
top-rot, 46 per cent of the felled trees were infected with butt-rot, 
the bulk of which was also caused by Polyporus pilotae. 

RATE OF GROWTH. 

The chestnut bark disease was not found hi the region examined, 
but the chestnut trees, and also the oaks and poplars, were undoubt- 
edly dying here and there from other causes. The annual rings 
in the chestnuts show that these trees had made a fairly rapid and 
vigorous growth during the first 20 or 30 years; then came a period 
of much slower growth, culminating in a period in which the annual 



Bui. 89, U. S. Dept. of Agriculture. 



Plate I. 




Fig. 1.— Heart-Rot in Chestnut Caused by Polyporus Pilotae. 

The fungus entered at the dead branch and has moved downward into the heartwood of the 

tree proper. 




Fig. 2.— "Shoe Strings" of Armillaria Mellea beneath the Bark of a Felled 
Chestnut Which had been Killed by This Fungus. 



Bui. 89, U. S. Dept. of Agriculture. 



Plate II. 




Fig. 1. 



'Shoe Strings" of Armillaria Mellea on the Dead 
Roots of a Wind-Thrown White Oak. 




Fig. 2.— Armillaria Mellea under the Bark of Two Chestnut 
Trees Which are Joined at the Ground. 

The fungus lias killed the tree in the foreground and has passed over to 
the other tree, where it has killed the bark for a distance of 8 feet up- 
ward and about one-third of the distance around the base of the tree. 



DEATH OF CHESTNUTS AND OAKS. 8 

increment was less than 1 millimeter in radius. In those trees 
which had been killed the annual increment in radius for the last 
6 to 10 years of their life was only one-third to one-fourth of a milli- 
meter. The average rate of increment was found to be 25 milli- 
meters in diameter for 1\ years of growth. This small increment 
indicates that the chestnut in this region is growing under very 
unfavorable conditions. 

A clearer idea of how slowly these chestnuts have grown can be 
obtained by comparing the diameters of a few of these trees with 
those of chestnuts grown under more favorable conditions in Other 
localities. For this purpose data are used which were published in 
1905 by the Bureau of Forestry in Bulletin 53, entitled "The 
Chestnut in Southern Maryland/' by Raphael Zon. The Forest 
Service has permitted the writer to use some unpublished data con- 
sisting of growth-diameter measurements made in West Virginia and 
Tennessee by Walter Mulford in 1905-6 and in Hyde Park, Dutchess 
County, N. Y., by J. G. Peters in 1905. The data from Hyde Park, 
where the growth conditions for chestnuts were favorable, are espe- 
cially valuable for comparing with the growth data of chestnuts in 
New Berlin, as the two localities are in the same State. The growth 
data of chestnuts grown -in Connecticut, included in Table I, were 
obtained by compiling the figures contained in Bulletin 154 of the 
Connecticut Agricultural Experiment Station, entitled "Chestnut 
in Connecticut and the Improvement of the Woodlot," by Austin F. 
Hawes. 

Table I. — Diameter measurements and average ages of chestnut trees. 
Diameter, Breast High (Inches). 





New York. 


Connecti- 
cut. 


Mary- 
land. 


Tennes- 
see. 


West 
Virginia. 


Age and diameter. 


New 
Berlin. 


Hyde 
Park. 


Age (years): 

10 


1.6 
3.7 
5.7 
7.6 
8.3 
9.5 
10.7 
11.9 
12.0 
11.2 
11.3 


2.5 
4.9 
7.2 
9.4 
11.4 
12.9 
14.0 




3.75 
6.67 
9.25 
11.5 
13.4 
15.2 
17.3 
18.1 
19.1 
20.0 


0.7 

3.1 

5.6 

8.2 

11.2 

13.7 

16.0 

18.4 

20.3 

21.7 

22.7 


0.5 


20 


3.4 
6.4 
9.5 
12.6 
15.6 
18.7 
21.7 
24.8 
27.8 
30.8 


2.4 


30 


4.3 


40 


6.4 


50 


8 4 


60 


10.4 


70 


12.5 


80 


14.4 


90 




16.3 


100 




18.2 


110 




19.9 











Age (Years). 



Diameter, breast high (inches): 



32 


25 


29 


17 


32 


46 


31 


35 


25 


39 


56 


38 


39 


29 


44 


65 


43 


42 


33 


46 


80 


47 


45 


38 


49 


90 


54 


48 


43 


53 



4 BULLETIN 89, TJ. S. DEPARTMENT OF AGRICULTURE. 

From Table I it is readily seen that the chestnut at New Berlin, 
X. Y.j has made a much slower growth than the trees from any of 
the other localities listed. 

GENERAL CONDITION OF THE WHITE OAK. 

Of the oaks in this region, the white oak (Quercus alba) predomi- 
nates, but is intermixed with the red oak (Q. rubra). The tops of all 
the oaks appeared healthy, no "stag heads" or large dead branches 
being present. There was very little butt-rot of any kind in the boles. 
This was especially true of the area that had never been logged. In 
this area there occurred only 5 per cent of butt-rot and no top-rot of 
any kind. On the area which had been partially logged once there 
was a greater percentage of butt-rot due to injury to the standing 
timber from bruises on the roots and butts of the trees exposed to 
injury in logging. On this area the oak had 21 per cent of butt-rot, 
as against 5 per cent on the unlogged tract. Of this butt-rot, 87 per 
cent was caused by Hydnum erinaceus, which by decay makes hollows 
and is capable of entering through slight bruises on the trees, as well 
as through fire scars and other deep wounds. 

ARMILLARIA MELLEA ON CHESTNUTS, OAKS, AND POPLARS. 

The "shoe strings " of ArmiUaria mellea were found very abundantly 
on the roots and under the bark of the butts of chestnuts, oaks, and 
poplars. They were also occasionally found on maples and on service 
berries (AmelancMer sp.), but none were found on the white pine. 
These "shoe strings" were also common in the soil around the bases of 
the diseased and dead trees. On some of the dead chestnut trees 
these "shoe strings" had grown upward under the bark for 15 or 20 
feet. In many instances they had made a perfect network of strings 
over the sapwood (PL I, fig. 2). There could be no reasonable doubt 
that this fungus was killing the chestnut and oak, since trees were 
found in all stages of decline when it was present. Wherever a 
dead piece of bark on the base of a tree was removed, the brown or 
black rhizomorphs of this parasite were found beneath it. In such 
cases a watery zone of dying bark of a dark-brown color marked the 
boundary fine between sound and diseased tissue. Sometimes only a 
very small area of the bark was affected, although the roots on this 
side of the tree were already dead and the outer layers of the sap- 
wood were more or less decayed. The rotten sapwood is watery, 
white in color, soft, and easily broken. On a chestnut tree 18 inches 
in diameter this fungus had killed an area 14 inches wide at the 
ground and extending 15 feet upward, while the "shoe strings" had 
grown up under the bark a distance of 8 feet. The top of this tree 
was dead. In three instances where chestnut trees had been struck 



DEATH OF CHESTNUTS AND OAKS. O 

by lightning this disease was found following up and enlarging the 
wounds. Many of the white oaks killed by this fungus had been 
blown down, In every case the upturned roots were covered with a 
network of the black rhizomorphs (PI. II, fig. 1). Several groups of 
two to four chestnut trees which had originated from sprouts around 
a common stump vere found killed by this root-rot. Plate II, figure 
2, shows two trees a'om a common base, one being already dead 
and the other badly diseased. In the latter the bark and roots on 
the side adjacent to the dead tree were killed for about one-third of 
the distance around the base, and the rot had extended up the tree 
8 feet under the bark. 

PERCENTAGE AND SIZE OF CHESTNUTS KILLED BY ARMILLARIA MELLEA. 

Of the 302 felled chestnut trees examined, 64, or 21 per cent, had 
been killed by the Armillaria root-rot. The average diameter of these 
killed trees was 12 inches; the largest chestnut killed was 26 inches 
and the smallest 3 inches in diameter. Trees of all diameters be- 
tween these limits were found diseased and killed. Of these trees, 
10 had a diameter of 3 to 5 inches, 13 of 6 to 10 inches, 22 of 11 to 
15 inches, and 19 of 16 to 26 inches. From this it follows that a 
greater percentage of the large chestnut trees was killed by this root- 
rot than of the smaller and younger trees. Of the 64 chestnut trees 
killed, 41, or 64 per cent, were over 10 inches in diameter. The 
average diameter of these 41 trees was 16 inches. In the white oak, 
just the reverse occurred; a greater percentage of the smaller and 
younger trees was killed than of the larger and older ones. 

PERCENTAGE AND SIZE OP OAKS KILLED BY ARMILLARIA MELLEA. 

Of the 477 oaks checked, 130, or 27 per cent, had been killed by 
the Armillaria root-rot. The average diameter of these killed trees 
was 7 inches, as compared with 12 inches in the chestnut. The 
largest oak killed was 18 inches and the smallest 2 inches in diameter. 
Trees of all sizes between these two extremes were affected. Of 
these white oaks, 39 ranged in diameter from 2 to 5 inches, 70 from 6 to 
10 inches, and 20 from 11 to 15 inches, with only 1 over 15 inches. 
Of these 130 white oaks which had been killed, 84 per cent were less 
than 11 inches in diameter and only 16 per cent were over 10 inches 
in diameter, as compared with 64 per cent in the case of the dead 
chestnut trees in the same locality. 

Of the white oaks killed by this root-rot, 46 had been overthrown 
by the wind, while only 2 of the dead chestnuts had been blown 
down. Of the wind-thrown oaks, 26 were from 6 to 8 inches in 
diameter, showing that the smaller as well as the larger sizes of white 
oaks were not as easily uprooted as those of medium diameter. 
34907°— 14 2 



6 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE. 

NUMBER AND SIZE OF POPLAR TREES KILLED BY ARMILLARIA MELLEA. 

Ill addition to the dead chestnuts and oaks, the writer counted 29 
poplar trees which had been killed by this root-rot out of a total 
of 45 examined. Many of these were small and much suppressed, 
although there were 12 that ranged from 6 to 9 inches in diameter. 
These larger poplars were not suppressed and under normal condi- 
tions ought not to have died. 

GENERAL DISCUSSION OF THE DISEASED CHESTNUTS AND OAKS. 

Why a larger percentage of small white oaks should be killed than 
of small chestnut trees is difficult to explain from the data at hand. 
However, it seems to be evident, judging from the location of the 
smaller white oaks which were killed, that the majority of the trees 
under 1 1 inches in diameter were much suppressed and for this reason 
would perhaps succumb more quickly to disease than trees growing 
under more favorable conditions. Nothing was found to indicate that 
the larger white oaks which had been killed were in poor health 
before they were attacked by this disease. It would seem that the 
disease, having gained a foothold in the soil, simply spread to the 
large white oaks and finally killed them. As far as could be deter- 
mined, the fungus Armillaria mellea was the primary cause of their 
death. No white oaks in this region were seen which had been 
struck by lightning; this was in marked contrast to the number of 
chestnut trees in the same territory which had been struck. 

The only explanation which can be offered for the small percentage 
of young chestnut trees which had been killed by the root-rot is that 
the present stand of chestnuts originated mainly from sprouts, and 
the young trees therefore had the large root system of the parent 
stump from which to draw nourishment. As a result, their growth 
would be very vigorous during the first 10 or 15 years of life. Under 
such conditions one would not expect a hemiparasite like Armillaria 
mellea to attack them as readily as it did the suppressed young oaks. 
This, however, does not explain why the disease has killed so many 
of the older and larger chestnut trees, unless the old stumps acted' 
as a breeding ground for the mycelium until it obtained a foothold 
in the living trees. The chestnuts undoubtedly were growing under 
unfavorable conditions, a fact proved by the very small annual incre- 
ment. This would make them more subject to diseases of this type. 
The weather conditions in the past may have been such as to weaken 
the trees and thus make them more susceptible to this rot. For 
instance, in the year 1913 the chestnut trees had lost two sets of leaves 
from late frosts, and at the time this investigation was made (June 
19, 1913) the third set of leaves was not fully developed, and many 
of the trees were so badly injured that they apparently were not 
going to leaf out at all. 



DEATH OF CHESTNUTS AND OAKS. 7 

AREAS INFECTED BY ARMILLARIA MELLEA. 

Ten distinct badly diseased areas of varying sizes were found in 
which the Armillaria root-rot had killed many trees. On one area 
40 yards in diameter, both chestnuts and oaks of large size had been 
killed, including 6 chestnuts with diameters of 8, 8, 10, 12, 14, and 
16 inches, and 4 oaks with diameters of 8, 13, 14, and 14 inches, re- 
spectively. Another rather large area had 34 dead trees scattered over 
it; of these there were 25 white oaks, 6 chestnuts, and 3 poplars. 
These trees ranged from 3 inches to 26 inches in diameter. On none 
of these diseased areas were all of the trees killed; some were alive 
and apparently in good health. This root-rot apparently was much 
worse where the soil was very damp, or even wet, during certain 
portions of the year. 

Mr. H. M. Sears, of the Forest Service, in a report entitled "Deteri- 
oration of Blight-Killed Chestnut in Northern New Jersey," mentions 
the presence of the rhizomorphs of Armillaria mellea beneath the 
bark of some of the dead chestnut trees. No evidence was advanced, 
however, to show that this fungus had attacked the chestnut trees 
before they died. 

ARMILLARIA MELLEA ON CHESTNUTS IN NORTH CAROLINA. 

AREA EXAMINED. 

On a recent trip through North Carolina, the writer found a rhizo- 
morphic root-rot prevalent on the chestnut near Mount Airy, N. C, 
which is apparently the same as that found in New York. As the 
investigations in North Carolina were devoted primarily to the heart- 
rots of trees, very little time was given to this root-rot problem. 
However, some data on the character and extent of the disease were 
taken. The area studied was located about 6 miles east of Mount 
Airy, near Brim, N. C. 

CHARACTER AND GENERAL CONDITION OF THE TIMBER. 

The timber was located on the ridges and slopes and consisted of 
a mixed stand of chestnut and oak growing in a rather thin, more or 
less rocky soil with a red-clay subsoil. Chestnut oak (Quercus prinus) 
was the principal species of oak, but white oak (Q. alba), black oak 
(Q. velutina), and red oak (Q. rubra) were also present. All of the 
chestnut over the area examined was deteriorating, 90 per cent was 
stag headed and much was actually dying, while from 20 to 30 per 
cent was already dead. There was little or no sprout reproduction 
from the bases of the affected trees. Because of the rotted condition 
of the roots, the dead and dying trees in this region are easily blown 
down. According to resident millmen, this dying of the chestnut has 
become very pronounced during the last fifteen to twenty years. 



8 BULLETIN 89, U. S. DEPARTMENT OF AGRICULTURE. 

The chestnut over this area originated mainly from seedlings, and, 
judging from the large annual increment, it made a healthy and 
rigorous growth before this trouble appeared. 

NUMBER AND CONDITION OF THE INDIVIDUAL TREES EXAMINED. 

The roots of 71 dead or badly diseased trees were examined. Of 
this number, 64 were chestnuts, 5 black oaks, 1 a chestnut oak, and 1 
a sassafras. Of the chestnuts, 55 were already dead and 23 of them 
had been blown down when the studies were made. This afforded 
an opportunity to examine the condition of the roots. Nine of the 
living chestnuts studied were either dying or badly stag headed. 
Chestnut trees of all sizes were found dead or dying. Of the 64 
chestnuts studied, 7 ranged in diameter from 4 to 10 inches, 23 from 
11 to 20 inches, 29 from 21 to 30 inches, and 5 had diameters greater 
than 30 inches. An occasional black oak was found dead or badly 
stag headed, especially when adjacent to the worst affected chestnuts. 
The chestnut oaks, however, seemed to be vigorous and in the best 
of health. Especially valuable data were obtained from a wind- 
thrown chestnut 38 inches in diameter, which had been living but 
was badly stag headed when blown down . This tree was blown down 
only 11 days before the data were taken. The condition of its roots 
and stool was, therefore, exactly the same as when alive. When this 
tree was overthrown, several of the most superficial roots were still 
alive, but all of the deeper roots were dead. The sap wood of the 
dead roots was white rotted and covered with a network of black 
rhizomorphic strands. This rot was gradually encroaching on the 
living roots and killing them. The tree stood on the top of a rocky 
red-clay ridge, with the bulk of its roots within 2 feet of the surface 
of the soil. 

All of the 71 trees examined had the "shoe strings" of Armillaria 
mellea on their roots. They were also found in a few instances ex- 
tending from 3 to 8 feet upward beneath the bark on both living and 
dead trees. As a rule, however, the rhizomorphs were inconspicuous 
and were confined mainly to the roots and stools of the affected trees. 
The area studied was very limited, and no attempt was made to 
examine the roots of a large number of living trees. The data given 
here are therefore too meager to justify any positive opinion as to the 
amount of damage done by this root-rot in North Carolina. How- 
ever, the prevalence and apparent destructiveness of this fungus over 
the area examined seem to point to it as very probably an important 
factor in the gradual recession of the chestnut in that State. If such 
an organism is at work, it would in a large measure explain the 
hitherto unexplained phenomena associated with this recession, 
such as the lack of reproduction from sprouts and the failure of the 
chestnut to reoccupy its former territory. A more extended investi- 



DEATH OF CHESTNUTS AND OAKS. 9 

gation covering the entire range of this recession may or may not 
show the presence of this root-rot as abundantly over the other 
regions involved as it is at Brim. The identification of this root- 
rotting organism as it occurred both in New York and in North 
Carolina was made from the rhizomorphic strands present on the 
affected trees. No sporophores were found, as the time of the year 
during which the diseased trees were examined was not the proper 
season for their appearance. 

CONCLUSIONS. 

(1) The chestnut near New Berlin, N. Y., and at Brim, N. C, is 
deteriorating. This is clearly shown by the small annual increment 
during recent years, by the thin sapwood, by the large percentage of 
diseased and stag-headed tops, and by the number of dead and dying 
trees. This decline is probably due to several factors, one of which 
is the root-rotting fungus Armillaria mellea, but it should be noted 
that in spite of these facts the chestnut bark disease (EndotMa para- 
sitica) is not present in these localities. 

(2) Armillaria mellea can become an active parasite under favor- 
able conditions, especially in chestnuts and oaks, killing not only 
suppressed trees in the forest, but also those that are growing under 
more favorable environments. 

(3) The prevalence and apparent destructiveness of this fungus 
over the area examined in North Carolina seem to point to it as very 
probably an important factor in the gradual recession of the chestnut 
in that State. 

o 




BULLETIN 




No. 90 



Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
May 19, 1914. 



THE ROSE APHIS. 1 

By H. M. Russell, 
Entomological Assistant, Truck Crop and Stored Product Insect Investigations. 

INTRODUCTION. 

Because of its beauty, and its hardiness as an outdoor plant, the rose 
has long been one of the most popular ornamental flowers in this 
country. Yet in spite of the appreciation given it the blossoms and 
young foliage are frequently permitted to suffer great damage from 
the rose aphis ( MacrosipTium rosse L.), whereas a few minutes' atten- 
tion on the part of the owner each week would remedy the injury 
and greatly increase the beauty of the bloom and f oliage. This com- 
mon rose pest was first described by Linnaeus 2 in 1735, and since 
that time has often been mentioned in systematic works by both 
European and American writers. However, the writer has seen no 
account of it in American entomological publications in which the 
life history, habits, or control have been treated with anything 
approaching completeness. The writer, therefore, in 1910, while sta- 
tioned at Los Angeles and under the direction of Dr. F. H. Chitten- 
den, began a study of the life history and habits of the rose aphis 
in its occurrence on the outdoor roses so largely grown in southern 
California. At a later period the work was carried on to some extent 
in Washington, D, C. While this study is still incomplete, enough 
has been learned to give the rose lover a fair understanding of the 
habits of this insect and of the means for controlling it. 

RECENT RECORDS. 

During the fall and winter of 1909 and the spring of 1910 the 
writer found the rose aphis attacking roses and causing extensive 
damage to the buds and blossoms throughout the city and in the 
vicinity of Los Angeles. On October 21, 1909, when first observed, 

1 This bulletin is of interest to rose growers everywhere, 
s Linnaeus, C, Systema Natur., ed. 12, vol. 1, pt. 2, p. 734, 1767. 
34854°— 14 



2 BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

this insect had become quite common, and many of the buds were 
covered with the females and young. Examination of surrounding 
localities disclosed the same conditions of infestation. The aphides 
increased rapidly until the cold weather in December checked, 
although it did not entirely stop, their reproduction and growth. In 
January, warmer weather again prevailing, the rosebushes began to 
grow rapidly, and the rose aphis became very abundant on the tender 
stems and buds. It continued abundant and developed rapidly dur- 
ing the months of February and March, although syrphus-fly larvae 
devoured thousands. Early in April, however, there occurred sev- 
eral very warm days when the temperature rose to 100° or 101° F., 
and immediately the numbers of aphides were greatly reduced. 
Afterwards the aphis occurred scatteringly on the roses and caused 
very little damage. This was due in part to extreme heat and the 
work of parasitic and predaceous enemies, and to the fact that in 
June the roses became more or less dormant and ceased active 
growth for some weeks. By the middle of August the rosebushes 
had resumed active growth, and this insect again began to increase 
rapidly and to cause damage, continuing to multiply and injure the 
roses until October 1, 1910, when observations ceased. 

At Washington, D. C, during October and November, 1912, this 
aphis was very abundant and injurious to roses grown in the yards 
and gardens of the city. But by November 29 only a few aphides 
remained on the plants, although these persisted as late as Decem- 
ber 16. 

DESCRIPTION. 1 

The rose aphis occurs in two forms, one in which the body is of a 
pinkish color and the other in which the pink is replaced by bright 
green. Both forms may be present on the same bush or twig, and in 
some cases all on one bush may be green and all on another near it 
pink. It would appear from the writer's observations that the green 
aphides are much more abundant during the cooler months than the 
pink forms. 

The winged female (fig. 1, a) has a pear-shaped body which in one 
form is pinkish and in the other bright green. The thorax is largely 
black, apparently deeper black in the green form, and there is a row 
of black spots on either side of the abdomen. These colors may vary 
slightly in shade. The antennae, cornicles, ends of femora, and the 
tarsi are black, while the other parts of the legs are whitish. In both 
pink and green forms, however, the head may be entirely black, and 
the black antennae and cornicles may be hyaline at the tips. The 

1 Another aphis commonly found on the ros6 is known as the small green rose aphis {Myzus rosanim 
Walk.), but this can be distinguished by its smaller size and by the fact that it has only a green form. 
This species i:; shown in figure 2, in both winged state (a) and wingless state (6) with many dotails of struc- 
ture. This aphis will yield to the same treatments as the common rose aphis. 



THE EOSE APHIS. 



eyes are dark red, the cauda is yellowish, and the veins of the wings 
are light yellow. The legs, antennae, and cornicles are very long and 
slender, the antennae longer than the body. The length of the body 
is about one-twelfth of an inch (2.5 mm.) from the front to the tip of 
the cauda and the length of wing about one-sixth of an inch (4.2 mm.). 




--x^ 



Fig. 1. — The rose aphis (Macrosiphum rosse): a, Winged viviparous female; b, wingless viviparous female; 
c, e , g, third antennal article, cornicle, and style, respectively, of winged female; d, f, h, same of wingless 
female. Greatly enlarged. (After Essig.) 

In the wingless female, also (fig. 1, b), the body is pear shaped, 
more or less blunted at the posterior end, and pinkish or bright green 
in color. The eyes are red. The antennae are as long as the body 
and very light green. The cornicles and legs are long and slender 
and light green. The length of the body is about one-twelfth of an 
inch (2.5 mm.). 



4 BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

DISTRIBUTION. 

The rose aphis is distributed over the entire United States, having 
been recorded from Massachusetts, New Jerse} , Illinois, Iowa, Minne- 
sota, Colorado, and California. It also occurs in Europe, from which 
country it was first described. 

The writer has collected it in southern California on all the 
commoner varieties of roses growing outdoors and has also taken it, 
in 1913, in Connecticut, Maryland, the District of Columbia, and 
Virginia. 




Fig. 2. — The small green rose aphis ( Myzus rosarum): a, Winged viviparous female; 6, wingless viviparous 
female; 1, 2, antcnnal articles of winged female; S, cornicle of same; 4> style of same; 6, third antenna! 
article of same; 6', style of wingless female; 7, 9, front and antenna of same; 10, cornicle of same; S, process 
of sixth antenna! article of same. Greatly enlarged. (After Essig.) 

CHARACTER OF INJURY. 

This insect, like all aphides or plant-lice, obtains its food by suction. 
The slender beak with which it is furnished is inserted into the plant 
attacked, and through this the plant juices are taken up. The rose 
aphis in feeding chooses the tender and growing shoots and flower 
buds or the young unfolding leaves, and by feeding in large numbers 
checks the growth, the leaves and flowers being curled or distorted 
and prevented from attaining their perfect form. (Pis. I, II.) 



Bui. 90, U. S. Dept. of Agriculture. 



Plate I. 




Rose Buds Showing Injury by the Rose Aphis (Macrosiphum rosae). Enlarged. 

(Original.) 



Bui. 90, U. S. Dept. of Agriculture. 



Plate II. 




THE ROSE APHIS. 5 

Because of the feeding of this rapidly reproducing insect, the flowers 
may be largely spoiled for decoration, or, since the rose aphis, like 
all aphides, secretes a sweet sticky liquid called honeydew, the appear- 
ance of the foliage may be ruined because of the sooty mold that 
develops where this honeydew has collected. 

HABITS. 

About the time the wingless females become ready to reproduce 
they leave the parent colony and crawl or migrate to various parts 
of the rosebush. Upon finding a growing twig or bud, the female 
settles down with the head pointed toward the ground and begins 
to feed. In a day or two she begins to give birth to young, which 
ordinarily range themselves close together around the tender bud 
or stem behind the adult, and with the heads all pointing downward 
begin feeding. (PL II.) As the stem or bud becomes crowded 
many move out until the flower itself is covered with them. As the 
aphides continue feeding a large amount of honeydew is produced 
which falls to the leaves beneath, causing a disagreeable stickiness 
on the leaf, which either becomes covered with dust or black from 
sooty mold. 

A very slight jar causes the aphides to let go with one pair of legs, 
and all begin to twitch from side to side on the remaining four legs 
until quiet is restored, while a severe jar causes many to fall to the 
ground. A number of the young develop wings, and when mature 
they fly to other buds and form new colonies. 

When the nymph changes to the winged form the skin splits 
along the dorsum and the adult crawls slowly out. When newly 
transformed the adult is light reddish or green in color, with antennae, 
beak, legs, and cornicles whitish or hyaline, and the wings, which are 
also white in color, appear as little sacks on the back. In about 
20 minutes the wings become fully expanded, and two days later the 
aphis has the colors of the mature insect. 

LIFE HISTORY AND REPRODUCTION IN CALTCORNIA. 

In a climate as mild as that of southern California this insect 
reproduces continuously throughout the year and undoubtedly is 
capable of reproducing asexually and viviparously for an extended 
period. While under observation it has been found giving birth to 
living young throughout the entire year, and the writer has been 
unable to find eggs during the same period. It may be that in a 
climate such as exists in that part of the country, where very cold 
weather does not occur and where the roses continue to grow all 



6 BULLETIN 90, U. S. DEPARTMENT OP AGRICULTURE. 

winter, sexual forms and eggs of this species are not produced, at 
least until parthenogenetic reproduction causes deterioration. 1 

In other parts of this country where the winter conditions are more 
severe the rose aphis passes the winter in the egg stage. At Wash- 
ington, D. C, on November 29, 1912, the writer found a few eggs 
of this species laid on the twigs of rosebushes. These small, oval, 
shining black eggs were fastened to the sides of dormant buds. 

Buckton 2 described the eggs as follows: 

The eggs are at first yellow, but subsequently they become black by reason of 
certain changes shown by Balbiani to result from fecundation. Previous to this time 
the outer coats are sufficiently thin and transparent to allow the process of segmentation 
to be observed. 

Notwithstanding the great size of the ovum the female may carry five or more. 
These, however, are not equally large, but are found to vary in bulk as they approxi- 
mate maturity and the time for expulsion. 

In California during the fall and spring, while the rose shoots are 
growing vigorously and producing much tender growth, the rose 
aphis reproduces very rapidly. During the summer, however, the 
rate of reproduction seems to be much reduced, and, owing to the 
attack of natural enemies, this insect does not greatly increase. 
In the winter the time of development is lengthened and the rate 
of reproduction is considerably less. 

During the months from October, 1909, to March 10, 1910, the 
author endeavored to ascertain the number of young produced and 
the average rate of reproduction under normal conditions. This 
was done by marking rose twigs having a single female and, after 
examining them every other day, removing all the young born at that 
time. Thus the aphides were exposed to temperature, rain, and 
all other natural conditions which might influence them. Under 
this method many females were knocked from the bushes and lost, 
but as this would occur naturally it demonstrates fairly well the 
average rate of reproduction, if not the maximum, under the condi- 
tions most favorable for the adult. These records have all been 
included in Table I. 

1 B. M. Lelong, in the Report of the State Board of Horticulture for California, for 1889, page 213, states 
that " Kyber, in 1815, has had the rose aphis producing young for four years. From his carefully conducted 
experiments and from corresponding ones made by other naturalists a law has been educed, which we dare 
not destroy, ' that under certain circumstances, a female aphis may without coupling continue propagating 
to infinity, provided that the necessary conditions for the development of the young — food and heat — are 
not wanting.' " 

s Buckton, G. 15., Monograph of the British Aphides, vol. 1, p. 107-108, 1875. 



THE EOSE APHIS. 



Table I. — Re-production and development of the rose aphis, Macrosiphum rosae, in 
southern California, 1909-10. 



Date of birth of female unknown; 

gave birth to first young Oct. 20, 

1909: Number of 

young. 

Oct. 20 4 

21 5 

22 5 

23 7 

24 5 

25 7 

26 : o_ 

Total 33 

Average per day 5£ 

Date of birth of female unknown; 
date of birth of first young un- 
known: 



Nov. 



Total. 



6 

4 

2 

4 

■ _0)_ 

10 

Average per day 3+ 

Female born Nov. 18, 1909; gave 
birth to first young Dec. 6, 1909: 2 

Dec. 6 1 

8 5 

10-11 6 

12 3 

13-14 4 

15-10 9 

17 2 

18-19 3 

20-21 6 

22-23 5 

25 2 

28 («) 



Total 46 

Average per day 2 \ 



Date of birth of winged female, red 
form, unknown; date of birth of 
first young unknown: 

Nov. 18 4 18 

19 3 

20 5 

21-22 12 

23 10 

24 _C)_ 

Total 48 

Average per day, about 6 

1 Aphis lost. 

2 Period from birth to reproduction, 18 

3 Aphis dead. 



Date of birth of female unknown; 
gave birth to first young Nov. 

19, 1909: Number of 

young. 

19 2 

20 2 

21-22 4 



Nov. 



23. 
24. 
25. 
26. 
27. 
28. 
29. 
30. 



Total 22 

Average per day 2 



Date of birth of wingless female, 
green form, unknown ; gave birth 
to first young Nov. 19, 1909: 

Nov. 19 2 

20 5 

21-22 6 

23 5 

24 4 

25 3 

26 (? 5 ) 

27 4 

28 0) 



Total 

Average per day. 



29 
3+ 



Wingless female born Nov. 18, 1909; 
gave birth to first young Dec. 6, 
1909 : 2 

Dec. 7-8 3 

8 ( s ) 



10-11 3 

13 7 

15-16 7 

17 3 

18-19 6 

20 1 

21 ( 3 ) 



days. 



Total 30 

Average per day 2 

4 Up to date. 
6 Rain. 



Table L- 



BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

—Reproduction and development of the rose aphis, Maerosiphum rosae, in 
southern California, 1909-10 — Continued. 



Date of birth of female unknown; 

gave birth to first young Jan. 3, 

1910: Number of 

young. 

Jan. 3 2 

4 2 

6 9 

3 - P) 

Total 13 

Average per day 3 



Winged female, red form; gave birth 
to first young Mar. 3, 1910: 

Mar. 3 5 

4 5 

5 9 

6 5 



Winged female, red form; gave birth 
to first young Mar. 3, 1910 — Con- 
tinued. Number of 

young. 

7 5 

8 3 

9 P) 



Total 32 

Average per day 5 J 



Mar. 7. 

8. 

9. 

10. 



5 

5 
7 
P) 



Total 17 

Average per day 5| 



Two females were observed that produced 30 and 40 young, respec- 
tively, after which, they died under normal conditions. They pro- 
duced young on an average of 2 and 2\ per day for 15 and 20 days, 
respectively, during the month of December. Other females observed 
during the same period, but lost possibly before reproduction was 
completed, gave birth to from 15 to 45 young at an average of 2>\ per 
day. Two females observed in the month of March, however, pro- 
duced young at the rate of 5-| and 5§ a day, showing quite plainly 
how the reproduction was accelerated during the prevalence of 
warmer temperatures. Two females in October reproduced young 
at the rate of 5-| a day for 6 days, or until lost. 

From these observations it may be said that this insect is able to 
reproduce for at least 20 days during the winter in southern California 
and to give birth to as many as 45 young, while in the warmer seasons 
the number of young is probably greater and the period of reproduc- 
tion is considerably shorter. The reproduction experiments were too 
few in number to justify making any statements more generalized 
than these. 

LIFE HISTORY AND REPRODUCTION IN THE GREENHOUSE. 

During the fall of 1912 the rose aphis was under the direct observa- 
tion of the writer in the insectary greenhouse at Washington, D. C, 
and the life cycle was observed for a few individuals. 

A wingless female born October 10 matured and gave birth to young 
on October 19, or in 9 days. During the next 7 days she gave birth 
to 45 young, or an average of 6y per day. 



1 Aphis lost. 



THE EOSE APHIS. 9 

Of four other aphides, born on October 10, two became adult and 
gave birth to young on October 22, or in 11 days, while axiother 
required 12 days, and the fourth 13 days. 

Another aphis was born on October 19 and emerged as a winged 
female on November 3, reaching maturity in 15 days. This insect 
lived as an adult for 17 days and gave birth to living young for 14 days. 
During this time she gave birth to 87 young, or an average of 6^ per 
day. During this time the average mean temperature was 67° F. 

LIFE CYCLE IN CALIFORNIA. 

During the winter months of 1909-10 the life cycle was observed in 
California in a number of cases. Aphides born on the 18th of Novem- 
ber became adult wingless females and began to reproduce young in 
from 15 to 18 days, and in two cases the offspring of these same insects 
became mature and began to reproduce in from 18 days for wingless 
females to 21 days for winged females. Aphides born November 26 
emerged from nymphal skins as winged adults in from 23 to 25 days. 
Thus the wingless forms developed in all cases from 7 to 8 days sooner 
than winged forms. 

This was the maximum life cycle, and during the rest of the year 
the growth must have been much faster, but observations were not 
made owing to press of other matters. 

GENERATIONS. 

Taking 25 days as a maximum, this would allow more than 12 
generations annually, but with the shorter life cycle required during 
the warmer part of the year this number must be exceeded by at least 
7 or 8 generations. In greenhouses there are probably 25 to 30 
generations in a year. 

LONGEVITY. 

During the winter these insects are long lived for such delicate 
creatures. One lived under the direct observation of the writer for 
40 days and another for 33 days. Probably this is longer than for 
the same insect the rest of the year. 

NATURAL CONTROL. 

RAINS. 

In southern California the rainy season extends from about October 
1 to May or June. Usually before the rains set in the weather becomes 
cooler, but the rains are not as a rule hard and dashing, as are those 
so fatal to aphides in the East, and this apparently explains their 
slight effects as observed on the rose aphis. Undoubtedly some are 
washed away and destroyed by rain, but not to the extent occurring 
in the East, although reproduction seems to be greatly checked during 
a rainstorm. In the East this insect is many times nearly extermi- 
nated by a hard, dashing rain. 



10 BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

HEAT. 

During the early part of April, 1910, when the aphis was very abun- 
dant on the roses throughout the entire city of Los Angeles, three or 
four very hot days occurred during which the temperature rose as high 
as 100° F., and within a day or two thereafter the numbers of this 
aphis had become very much diminished. After this it did not seem 
to occur in large numbers again until about the middle of August. 

BIRDS. 

On March 19, 1910, the writer, with field glasses, watched a white- 
crowned sparrow (Zonotrichia leucophrys leucophrys) on a rosebush^ 
10 feet away, eating the rose aphides as fast as it could pick them 
from the bush. This was continued for fully 10 minutes, during which 
time many hundreds must have been eaten, as the plant was almost 
cleaned up by this bird. 

On March 30, 1910, a California house finch {Carpodacus mexicanu 
frontalis) was observed by the writer eating this aphis from a rose- 
bush for fully 15 minutes. 

PARASITIC INSECT ENEMIES. 

There are many different species of parasitic insect enemies that 
attack aphides, and some of these will attack the rose aphis. On 
June 13, 1910, many specimens of Macrosiphum rosse were found 
which showed signs of parasitism by an undetermined insect. These 
aphides were rounded and fastened to the underside of the rose leaves. 
The parasite when full grown had killed the host and, cutting its way 
out beneath the body, spun a tiny cocoon between it and the leaf. 
Unfortunately all of the parasites failed to emerge. While the para- 
site was not rare, at least during the past year, it did not seem to 
check the rose aphis to any extent. 

Ephedrus incompletus Prov., a braconid, was reared by the writer 
from this aphis at Washington, D. C, in 1912. 

PREDACEOUS INSECTS. 

Among the predaceous enemies the larvae of syrphus flies and lady- 
birds were observed feeding on the rose aphis, and without a doubt 
the most important check to this insect in 1910 was due to the larvae of 
syrphus flies. While these did not seem able to clear a plant alto- 
gether, still it was many times observed that strong thriving colonies 
of 50 to 60 aphides or more would be reduced by these insects in one 
or two days to a mere scattering here and there. During the year 
1910 five different species of Syrphidse were reared from larvae feeding 
on Macrosiphum rosx. These were Syrphus rlbesii L. (fig. 3), Syrphus 
opinator O. S., Allograpta fracta O. S., Eupeodcs volucris O. S. (fig. 4) 
and Lasiophthicus pyrasti L. 



THE ROSE APHIS. 



11 



The adults of all these species seemed to have similar habits. 
They flew swiftly from twig to twig and hovered over them in the 
bright sunlight, the wings moving with extreme rapidity, always with 
a distinct humming 

sound. From time * ~\ ,2j||^ (j ijls /) 

to time they alight- 
ed on the twigs or 
leaves and searched 
here and there for 
colonies of the 
aphis. The abdo- 
men was generally 
kept in throbbing 
motion, and when 
an egg was to be 
laid a long slender 
ovipositor was fig. 3 
thrust out and the 
egg was placed on 
a leaf or twig in the midst of or near the colony of the host insect. 
It was noticed that certain bushes shaded from the sun after 1.30 
p. m. were immediately deserted by these flies until the next day. 




■Syrphus ribesii, an enemy of the rose aphis: a, Fly; 6, lateral view 
of head; c, larva or active immature form; d, anal spiracles; e, thoracic 
spiracle of same. All much enlarged. (From Chittenden.) 




Fig. A.—Eupeodes volucris, an enemy of the rose aphis: a, Female fly; b, abdomen of male fly; c, hypopy- 
gium of male fly. Much enlarged. (From Webster and Phillips.) 

The rearing of five different species of syrphus flies from larvae 
found feeding on the rose aphis rather surprised the writer, and he 
regrets that lack of time has prevented a continuation of the work 



12 BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

that it might be ascertained if other species would also be commonly 
reared. 

Although the ladybird Hippodamia amoigua Lee. was observed 
during the entire time occupied by the observations on the rose aphis, 
it occurred in small numbers, and on only one or two occasions did it 
seem to be feeding on Macrosiphum rosx. 

DISEASE. 

On March 14, 1910, after a night of rain, one winged and two 
wingless aphides were found enlarged to fully five times their regular 
size, as if bloated. This was probably due to a fungous disease. 

EXPERIMENTS WITH REMEDIES. 

The abundance of the rose aphis is so marked in many years that 
frequently almost daily complaints of damage are made in the Dis- 
trict of Columbia and vicinity. Wherever it has been convenient or 
desirable to eradicate this species on small acreages of plants, water, 
applied with a garden hose or syringe, has been the remedy employed, 
not alone by the writer but by many persons resident in Washington. 
Indeed this treatment, which consists in directing a forcible stream 
of water against the affected portions of the plants has been one of 
the standard remedies advised. Experiments have been made by 
Dr. F. H. Chittenden, by Mr. C. H. Popenoe, and by Mr. A. B.Duckett, 
all in the District of Columbia and vicinity. In other regions, Mr. W. B. 
Parker has undertaken experiments with nicotine sulphate, and the 
writer has conducted quite a series of experiments with the same 
compound. Among other compounds used by Messrs. Chittenden and 
Popenoe for this species are aphis punk and other nicotine papers, 
always with gratifying success. While treating other forms of insects 
on roses, such as "slugs" and thrips, the aphides were always the 
first to perish. 

EXPERIMENTS IN THE DISTRICT OF COLUMBIA AND VICINITY. • 

On March 28, 1913, at Washington, D. C, four rosebushes in the 
greenhouse, well infested by the rose aphis, were sprayed with "black- 
leaf 40," a preparation guaranteed to contain 40 per cent of nicotine 
sulphate, in combination with whale-oil soap in the following formula: 

Nicotine sulphate ounce . . J 

Whale-oil soap pound. . £ 

Water : gallons. . 2\ 

Although the solution slightly injured the terminal buds and the 
tender shoots, the results were all that could be expected, 100 per 
cent of the aphides being killed. It is believed that the solution 
could have been reduced 25 per cent in strength with equally good 
results. 

' By A. B. Duckett. 



Bui. 90, U. S. Dept. of Agriculture. 



Plate III. 




Spraying Rose Bush with Compressed-Air Sprayer by Hand. 



THE EOSE APHIS. 13 

On April 23, at a Virginia station near Washington, a number of 
large rosebushes trained on the side of a house and well infested with 
aphides were sprayed. Both winged and wingless forms of aphides 
were present. Nicotine sulphate was applied, with and without the 
use of soap as in the previous formula, at the rate of 1 part to 1,000 
of water. In the experiments without the use of soap some diffi- 
culty was found in obtaining a spreading action of the spray, and con- 
sequently only about 90 per cent of the aphides were reached. It is 
believed that all reached by the spray were killed. When nicotine 
sulphate was used at the rate of 1 part to 1,400 parts of water 
and 1 part to 1,500 parts of water, results were not satisfactory, only 
about 25 and 10 per cent, respectively, being destroyed. With the 
use of soap 100 per cent of the aphides on the vines were killed, the 
results being very satisfactory. At the rate of 1 part of nicotine 
sulphate to 1,400 of water with a laundry soap added, 90 per cent of 
the aphides were killed; whereas the results with nicotine sulphate 
at 1 part to 1,600 of water and 1 part to 1,800 of water in combination 
with soap were unsatisfactory, only 70 per cent and 50 per cent being 
killed. 

In these experiments a compressed-air sprayer with Bordeaux type 
of nozzle was used at an estimated pressure of 90 pounds, and a fine 
but driving spray was employed. The water used for the dilution of 
the insecticide was particularly soft, but contained a very small 
proportion of sulphur. 

From these experiments it may be concluded that nicotine sulphate 
at the higher dilutions as used in these experiments is much more 
effective against the rose aphis when used in combination with whale- 
oil or other soaps, since the spreading action thus induced is much 
more favorable. The plants may, however, be injured in case the 
spray solution is too strong. It is not believed that the injury shown 
in the experiments was caused by nicotine sulphate used at too great 
a strength, since it has been applied experimentally to roses in the 
greenhouse at the rate of 1 part nicotine sulphate to 15 parts of water 
without injury other than the appearance of mildew, undoubtedly 
superinduced by the spraying. It is apparent from the results 
obtained that a spray can not be employed weaker than 1 part of 40 
per cent nicotine sulphate to 1,400 parts of water with satisfactory 
results unless in combination with whale-oil or other soap. 

ARTIFICIAL CONTROL IN THE GARDEN. 

Experiments have been conducted against the rose aphis with 
different nicotine extracts under different conditions as to strength 
and weather. In no case, in the writer's experience, were the plants 
injured, whereas the insect was destroyed in enormous numbers. 
The aphis is easily controlled by spraying with nicotine solutions 



14 BULLETIN 90, U. S. DEPARTMENT OF AGRICULTURE. 

containing 40 per cent of nicotine at the rate of 1 part of the solution 
to from 1,000 to 2,000 parts of water, with whale-oil soap at the rate 
of 1 pound to 50 gallons of spray mixture. When only a few rose 
bushes require treatment the spray may be prepared in small amounts 
as follows: To 1 teaspoonful of 40 per cent nicotine solution add 1 
to 2 gallons of water and one-half ounce of whale-oil soap. The soap 
should be shaved fine and dissolved in hot water. 

There are on the market numbers of solutions containing less nico- 
tine than the foregoing which may be used with good results with 
the addition of whale-oil soap, as advised, at the strength recom- 
mended by the manufacturers. If these are not obtainable, very 
good results may be accomplished by dissolving 1 pound of whale- 
oil soap or 2 pounds of common laundry soap in from 4 to 6 gallons 
of water. Wherever possible, however, the nicotine solutions should 
be used, as better results will be obtained. 

This species, like practically all of the green aphides, can also be 
controlled by repeated applications of a forcible stream of cold water. 
Since the roses in California and some other localities are much sub- 
ject to mildew, repeated use of this method has the disadvantage of 
increasing injury by this disease. In the case of the appearance of 
mildew, however, either through syringing with water or through 
the application of nicotine sulphate, this disease may be readily con- 
trolled by adding to the nicotine sulphate solution copper sulphate 
or blue vitriol at the rate of 1 pound to 50 gallons of water (approxi- 
mately 1 ounce to 3 gallons). A solution of copper sulphate used 
at this strength and sprayed on the plants after the application of 
the water treatment is effective in controlling the mildew. Another 
common practice of florists for the prevention of mildew is to dust 
the plants immediately after sprinkling or watering with common 
flowers of sulphur. 

In order successfully to fight this insect these sprays should be 
applied with a compressed-air sprayer (PI. Ill) or bucket pump 
capable of creating a fine penetrating spray. These pumps can 
usually be purchased at the seed stores at from $3.50 up to $15. The 
nicotine solutions are also carried by most seed stores. Where a 
pump is not to be obtained much can be accomplished by dipping 
the infested twigs into a pail of the solution of nicotine. 

From the experiments of the writer it is evident that this insect 
can be destroyed easily by the use of nicotine solutions of considera- 
bly less strength than have heretofore been used, but the treatment 
must 1)0 repeated at intervals to kill the aphides missed by former 
applications. With the different stylos of pumps now on the market 
at low prices no one who cares for roses has the slightest excuse for 
allowing them to be injured by this insect. 



THE EOSE APHIS. 15 

TREATMENT IN THE GREENHOUSE. 

For the treatment of the rose aphis as it occurs in greenhouses the 
nicotine solutions may be used, but at a lower strength than advised 
in the preceding paragraphs. Conditions vary somewhat, but it is 
believed that in most cases if the nicotine solution is used at the 
strength of 1 part to 2,000 of water it will not injure the rose plants 
if applied on a dark day or late in the afternoon so that the plants 
will not be exposed to reflected sunlight through the glass. 

When greenhouses containing different forms of plants are syringed 
with a forcible stream of water or with neutral soaps of the castile 
or similar types for the red spider and other insects, the rose aphis 
and other green aphides will also be killed. The same is true in 
regard to fumigations with hydrocyanic-acid gas for other rose pests. 
Directions for the use of hydrocyanic-acid gas for the fumigation of 
greenhouses and cold frames are given in Circular No. 37 of the 
Bureau of Entomology. In the experience of Dr. A. F. Woods, the 
author of that publication, the young growth of roses is particularly 
sensitive and has been more or less injured in experiments in the use 
of this gas. This is particularly true of such varieties as "Perle des 
jardins," "Mermet," and "Bride." 



ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

WASHINGTON, D. C 

AT 

5 CENTS PER COPY 



V 




BULLETIN OF THE 



No. 91 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief 
May 16, 191'4. 




COST AND METHODS OF CLEARING LAND IN THE LAKE 

STATES. 

By Harry Thompson, Agriculturist, and Earl D. Strait, Scientific Assistant 
Office of Farm Management. 

INTRODUCTION. 

Practically the entire northeastern part of Minnesota and all of 
Michigan and Wisconsin were originally forest land. Nearly all the 
southern parts of Michigan and Wisconsin are now cleared except for 
scattering farm wood lots. At the present time large areas of 
undeveloped land are found in northeastern Minnesota and the 
northern half of Michigan and Wisconsin. In Table I the figures 
showing the area of improved and unimproved lands were taken from 
the census of 1910; the statistics regarding the area of merchantable 
timber land and of logged-off land and the land values were compiled 
from data obtained from State, county, and township officials, 
lumber companies, and other companies or individuals well informed 
on these matters. The figures obtained furnish a fairly close ap- 
proximation to the actual acreage of merchantable timber and 
logged-off land in the three States mentioned. 

A part of the logged-off land in the three States specified probably 
would give better returns if put into permanent forest, but there is 
much good agricultural land in nearly every county in which these 
investigations have been conducted which at the present time is not 
growing desirable timber and is an idle waste (fig. 1), giving no re- 
turns whatever. Because of the danger from fire, these waste areas 
form a menace to the communities. 

At the present rate of cutting, most of the remaining merchantable 
timber will be cut within the next 25 years. This means that in many 
counties there will be a change from lumbering to farming. 

Note. — This bulletin gives details of cost and methods of clearing land in the Lake States and is of spe- 
cial interest to settlers in the logged-off sections of Michigan, Wisconsin, and Minnesota. 

36156°— Bull. 91—14 1 



2 BULLETIN 91, U. S. DEPARTMENT OF AGRICULTURE. 

Table I. — Acreage of improved {ayd imimpmvjsd lands, merchantable timber, and logged-off 
land and values of the improved and logged-off lands in the various counties of Michigan, 
Wisconsin, and Minnesota. 



State and count v. 



Michigan: 

Alcona 

•Vlger 

Alpena 

Antrim 

Arenac ' 

Baraga 

Bay' 

Benzie 

Charlevoix 

Cheboygan 

Chippewa 

Clare ' 

Crawford 

Delta 

Dickinson 

Emmet 

Gladwin 

Gogebic 

Grand Traverse 

Gratiot 1 

Houghton 

Iosco ' 

Iron 

Isabella J 

Kalkaska 

Kent i 

Keweenaw 

Lake 1 

Leelanau 

Luce 

Mackinac 

Manistee 

Marquette 

Mason 

Mecosta 1 

Menominee 

Midland ' 

Missaukee [ 

Montcalm 

Montmorency 

Muskegon > 

Newaygo ] 

Oceana 

Ogemaw 

Ontonagon 

Osceola 

Oscoda 

Otsego 

Ottawa 1 

Presque Isle 

Roscommon 

Saeinaw ' 

Schoolcraft 

Wexford 

All other counties ' . 



Total. 



Wisconsin: 

Ashland 

Barron 

Bayfield. .. 

Burnett 

Chippewa. . 

Clark 

Douglas 

Dunn 

Eau Claire. 
Florence. - . 

Forest 

Iron 

Langlade. . . 



Acreage. 



Value per acre. 



Improved. 



38, 037 
5, 634 
51,403 
78, 810 
55, 571 
9,344 

142, 635 
48, 856 
61,587 
50, 925 
79, 336 
53, 921 
10, 701 
42,932 
8,342 
54, 265 
54, 123 
4,742 

109,378 

248, 899 

35, 921 

40, 735 

9,008 

193, 124 
42, 563 

365, 717 
1,236 
33, 884 
83,812 
7,926 
21,118 
75,031 
23, 041 

100, 925 

159, 794 
64, 590 
94, 717 
60,918 

266, 401 
17,506 

109, 656 

166, 072 

151,782 
55,437 
11,992 

129, 303 
16, 218 
27,627 

247, 236 

39,925 

8, 951 

304, 738 

15, 431 

79,044 

,561,259 



24,400 

170,203 

21,700 

56,600 

106,000 

151,000 

19,900 

215,100 

185,861 

8,500 

6,100 

3,900 

47,800 



Unim- , Merchant 
proved, able timber. 



399 
583 
322 
225 
183 
577 
140 
152 
201 
413 
927 
318 
357 
705 
488 
256 
278 
720 
189 
121 
616 
324 
758 
172 
324 
184 
353 
336 
132 
580 
647 
284 

1,173 
215 
205 
611 
243 
311 
196 
341 
212 
378 
195 
315 
841 
239 
352 
310 
114 
393 
335 
225 
757 
290 

3,304 



668,000 
396, 197 
940, 200 
493,800 
468,900 
627, 600 
835,800 

311,100 
223,459 
309, 600 
889, 900 
503,0(10 
512,200 



3,000 

375,000 

1,200 

16, 000 



297, 280 



2,000 

16, 000 

43, 280 

233,360 



15, 000 
150,000 
174,397 

40, 200 

2,000 

597,327 

15,360 



217,200 
".366," 833' 



59, 640 
253,324 



7,000 
125,000 
173,440 

3,000 
500, 000 

2,000 



138, 338 



3,000 
42, 200 



8, 500 
2,000 
510,000 
1,760 
10,000 
70, 840 



9,960 
30,000 



100, 000 
33, 960 



4, 587, 261 



150, 000 

3,000 

200,000 

15,000 

46, 800 

1,250 

22,000 

1,000 

2,000 

93,500 

335, 0S5 

165,000 

240,000 



Logged-ofl. 



327 
125 
222 
179 
113 
240 

45 
132 
1 

300 
348 
293 
320 
450 
269 
174 
240 

69 
134 

50 
299 
232 
325 
122 
172 
134 

50 
296 

89 
225 
3"4 
231 
550 
144 

23 
372 
174 
211 
175 
161 
152 
240 
179 
260 
300 
215 
296 
196 

75 
245 
245 

72 
400 
226 



11,954,628 



450, 000 
400,000 
600,000 
265,000 
315,600 
625,000 
700, 000 
300,000 
113,000 
202,200 
490, 800 
335,000 
250,000 



Improved. 



S40to S60 
30 
25 
60 
60 
75 
100 
50 

40 up 

30 

50 to 55 
60 
35 
40 

75 to 100 

20 to 30 
40 

50 to 80 
50 



50 to 75 
20 to 50 
30 to 50 
60 
50 
65 
15 
30 to 50 
30 to 70 
50 
60 
40 
50 
50 
50 
50 

75 to 100 
20 to 50 
60 to 100 



20 to 



40 to 
25 to 



35 to 
25 up 
50 up 
40 to 
25 to 50 
50 
25 to 50 
20 to 40 
60 to 70 
30 to 35 
25 to 50 



50 



30 to 75 
25 up 



50 
to 60 
to 2 150 

50 
to 50 
to 100 
to 35 
to 35 
to 50 

50 

50 
to 100 
to 60 



Logged -off. 



S5to $15 

6 

10 

10 to 15 

10 

7 to 25 

15 to 25 

10 to 25 

10 up 

10 

6 to 25 

15 



7 to 
5 to 



10 to 



10 
5 to 20 

5 to 12 
10 to 15 

15 
30 
5 
15 
15 

6 to 20 
5 to 15 

15 
8 to 15 
12 to 15 
10 up 
3 to 15 
10 to 15 
5 to 20 
15 



3 to 



3 up 
10 up 
2.50 to 25 
10 
10 
20 
10 to 15 
8.50 to 15 
30 up 

10 
7.50 to 25 



5 to 15 

5 to 12.50 



3 to 35 

10 to 15 

3 to 2 100 

10 to 20 

12 to 20 

6 to 10 

5 to 10 

5 to 10 



7 t o 20 
4 to 10 
10 
3 to 25 
3 to 20 



iThe only timber in t be county is in farm wood lots. 



3 Orchard land. 



CLEARING LAND IN THE LAKE STATES. 



3 



Table I. — Acreage of improved and unimproved lands, merchantable timber, and logged-off 
land and values of the improved and logged-off lands in the various counties of Michigan, 
Wisconsin, and Minnesota — Continued. 



State and count} 7 . 



Wisconsin— Continued . 



Lincoln . 
Marathon . . 
Marinette . . 

Oconto 

Oneida 

Pepin 

Polk 

Portage 

Price 

Rusk 

Sawyer 

Shawano. . . 

Taylor 

Vilas 

Washburn. 
Waupaca... 
Wood 



All other counties . 
Total 



Minnesota: 

Aitkin 

Anoka 

Becker 

Beltrami 

Benton 

Carlton 

Cass 

Chisago 

Clearwater 

Cook 

Crow AVing 

Hubbard 

Isanti 

Itasca 

Kanabec 

Lake 

Mahnomen 

Marshall 

Mille Lacs 

Morrison 

Otter Tail 

Pennington 

Pine 

Polk 

Red Lake 

Roseau 

St. Louis 

Sherburne 

Wadena 

All other counties . 

Total 



Acreage. 



Improved. 



33,550 

184, 150 

79, 474 

134,000 

17,700 

70, 175 

149, 600 

218